Publications

@article{ksbs,

title = {Effect of water-wall interaction potential on the properties of nanoconfined water},

author = {Kumar, Pradeep and Starr, Francis W. and Buldyrev, Sergey V. and Stanley, H. Eugene},

url = {http://fstarr.web.wesleyan.edu/publications/ksbs.pdf},

doi = {10.1103/PhysRevE.75.011202},

issn = {1539-3755},

year  = {2007},

date = {2007-01-01},

journal = {PHYSICAL REVIEW E},

volume = {75},

number = {1, 1},

pages = {011202},

abstract = {Much of the understanding of bulk liquids has progressed through study of the limiting case in which molecules interact via purely repulsive forces, such as a hard-core or ``repulsive ramp'' potential. In the same spirit, we report progress on the understanding of confined water by examining the behavior of waterlike molecules interacting with planar walls via purely repulsive forces and compare our results with those obtained for Lennard-Jones (LJ) interactions between the molecules and the walls. Specifically, we perform molecular dynamics simulations of 512 waterlike molecules interacting via the TIP5P potential and confined between two smooth planar walls that are separated by 1.1 nm. At this separation, there are either two or three molecular layers of water, depending on density. We study two different forms of repulsive confinement, when the water-wall interaction potential is either (i) 1/r(9) or (ii) a WCA-like repulsive potential. We find that the thermodynamic, dynamic, and structural properties of the liquid in purely repulsive confinements qualitatively match those for a system with a pure LJ attraction to the wall. In previous studies that include attractions, freezing into monolayer or trilayer ice was seen for this wall separation. Using the same separation as these previous studies, we find that the crystal state is not stable with 1/r(9) repulsive walls but is stable with WCA-like repulsive confinement. However, by carefully adjusting the separation of the plates with 1/r(9) repulsive interactions so that the effective space available to the molecules is the same as that for LJ confinement, we find that the same crystal phases are stable. This result emphasizes the importance of comparing systems only using the same effective confinement, which may differ from the geometric separation of the confining surfaces.},

keywords = {Nanotechnology, Water},

pubstate = {published},

tppubtype = {article}

}

@article{rspcb,

title = {Polarizable contributions to the surface tension of liquid water},

author = {Jose L Rivera and Francis W Starr and Patrice Paricaud and Peter T Cummings},

url = {http://fstarr.web.wesleyan.edu/publications/rspc.pdf},

doi = {10.1063/1.2345063},

issn = {0021-9606},

year  = {2006},

date = {2006-09-01},

journal = {JOURNAL OF CHEMICAL PHYSICS},

volume = {125},

number = {9},

pages = {094712},

abstract = {Surface tension, gamma, strongly affects interfacial properties in 

 fluids. The degree to which polarizability affects gamma in water is 

 thus far not well established. To address this situation, we carry out 

 molecular dynamics simulations to study the interfacial forces acting on 

 a slab of liquid water surrounded by vacuum using the Gaussian charge 

 polarizable (GCP) model at 298.15 K. The GCP model incorporates both a 

 fixed dipole due to Gaussian distributed charges and a polarizable 

 dipole. We find a well-defined bulklike region forms with a width of 

 approximate to 31 A. The average density of the bulklike region agrees 

 with the experimental value of 0.997 g/cm(3). However, we find that the 

 orientation of the molecules in the bulklike region is strongly 

 influenced by the interfaces, even at a distance five molecular 

 diameters from the interface. Specifically, the orientations of both the 

 permanent and induced dipoles show a preferred orientation parallel to 

 the interface. Near the interface, the preferred orientation of the 

 dipoles becomes more pronounced and the average magnitude of the induced 

 dipoles decreases monotonically. To quantify the degree to which 

 molecular orientation affects gamma, we calculate the contributions to 

 gamma from permanent dipolar interactions, induced dipolar interactions, 

 and dispersion forces. We find that the induced dipole interactions and 

 the permanent dipole interactions, as well as the cross interactions, 

 have positive contributions to gamma, and therefore contribute stability 

 to the interface. The repulsive core interactions result in a negative 

 contribution to gamma, which nearly cancels the positive contributions 

 from the dipoles. The large negative core contributions to gamma are the 

 result of small oxygen-oxygen separation between molecules. These small 

 separations occur due to the strong attractions between hydrogen and 

 oxygen atoms. The final predicted value for gamma (68.65 mN/m) shows a 

 deviation of approximate to 4% of the experimental value of 71.972 

 mN/m. The inclusion of polarization is critical for this model to 

 produce an accurate value. (c) 2006 American Institute of Physics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{rspc,

title = {Polarizable contributions to the surface tension of liquid water},

author = {Rivera, Jose L. and Starr, Francis W. and Paricaud, Patrice and Cummings, Peter T.},

url = {http://fstarr.web.wesleyan.edu/publications/rspc.pdf},

doi = {10.1063/1.2345063},

issn = {0021-9606},

year  = {2006},

date = {2006-09-01},

journal = {JOURNAL OF CHEMICAL PHYSICS},

volume = {125},

number = {9},

pages = {094712},

abstract = {Surface tension, gamma, strongly affects interfacial properties in fluids. The degree to which polarizability affects gamma in water is thus far not well established. To address this situation, we carry out molecular dynamics simulations to study the interfacial forces acting on a slab of liquid water surrounded by vacuum using the Gaussian charge polarizable (GCP) model at 298.15 K. The GCP model incorporates both a fixed dipole due to Gaussian distributed charges and a polarizable dipole. We find a well-defined bulklike region forms with a width of approximate to 31 A. The average density of the bulklike region agrees with the experimental value of 0.997 g/cm(3). However, we find that the orientation of the molecules in the bulklike region is strongly influenced by the interfaces, even at a distance five molecular diameters from the interface. Specifically, the orientations of both the permanent and induced dipoles show a preferred orientation parallel to the interface. Near the interface, the preferred orientation of the dipoles becomes more pronounced and the average magnitude of the induced dipoles decreases monotonically. To quantify the degree to which molecular orientation affects gamma, we calculate the contributions to gamma from permanent dipolar interactions, induced dipolar interactions, and dispersion forces. We find that the induced dipole interactions and the permanent dipole interactions, as well as the cross interactions, have positive contributions to gamma, and therefore contribute stability to the interface. The repulsive core interactions result in a negative contribution to gamma, which nearly cancels the positive contributions from the dipoles. The large negative core contributions to gamma are the result of small oxygen-oxygen separation between molecules. These small separations occur due to the strong attractions between hydrogen and oxygen atoms. The final predicted value for gamma (68.65 mN/m) shows a deviation of approximate to 4% of the experimental value of 71.972 mN/m. The inclusion of polarization is critical for this model to produce an accurate value. (c) 2006 American Institute of Physics.},

keywords = {Water},

pubstate = {published},

tppubtype = {article}

}

@article{bps06b,

title = {Fractional Stokes-Einstein and Debye-Stokes-Einstein relations in a 

 network-forming liquid},

author = {Stephen R Becker and Peter H Poole and Francis W Starr},

url = {http://fstarr.web.wesleyan.edu/publications/bps.pdf},

doi = {10.1103/PhysRevLett.97.055901},

issn = {0031-9007},

year  = {2006},

date = {2006-08-01},

journal = {PHYSICAL REVIEW LETTERS},

volume = {97},

number = {5},

pages = {055901},

abstract = {We study the breakdown of the Stokes-Einstein (SE) and 

 Debye-Stokes-Einstein (DSE) relations for translational and rotational 

 motion in a prototypical model of a network-forming liquid, the ST2 

 model of water. We find that the emergence of fractional SE and DSE 

 relations at low temperature is ubiquitous in this system, with 

 exponents that vary little over a range of distinct physical regimes. We 

 also show that the same fractional SE relation is obeyed by both mobile 

 and immobile dynamical heterogeneities of the liquid.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{bps06,

title = {Fractional Stokes-Einstein and Debye-Stokes-Einstein relations in a network-forming liquid},

author = {Becker, Stephen R. and Poole, Peter H. and Starr, Francis W.},

url = {http://fstarr.web.wesleyan.edu/publications/bps.pdf},

doi = {10.1103/PhysRevLett.97.055901},

issn = {0031-9007},

year  = {2006},

date = {2006-08-01},

journal = {PHYSICAL REVIEW LETTERS},

volume = {97},

number = {5},

pages = {055901},

abstract = {We study the breakdown of the Stokes-Einstein (SE) and Debye-Stokes-Einstein (DSE) relations for translational and rotational motion in a prototypical model of a network-forming liquid, the ST2 model of water. We find that the emergence of fractional SE and DSE relations at low temperature is ubiquitous in this system, with exponents that vary little over a range of distinct physical regimes. We also show that the same fractional SE relation is obeyed by both mobile and immobile dynamical heterogeneities of the liquid.},

keywords = {Dynamic Heterogeneity, Glass Formation, Water},

pubstate = {published},

tppubtype = {article}

}

@article{ss06c,

title = {Model for assembly and gelation of four-armed DNA dendrimers},

author = {Francis W Starr and Francesco Sciortino},

url = {http://fstarr.web.wesleyan.edu/publications/ss.pdf},

doi = {10.1088/0953-8984/18/26/L02},

issn = {0953-8984},

year  = {2006},

date = {2006-07-01},

journal = {JOURNAL OF PHYSICS-CONDENSED MATTER},

volume = {18},

number = {26},

pages = {L347-L353},

abstract = {We introduce and numerically study a model designed to mimic the bulk 

 behaviour of a system composed of single-stranded DNA dendrimers. 

 Complementarity of the base sequences of different strands results in 

 the formation of strong cooperative intermolecular links. We find that 

 in an extremely narrow temperature range the system forms a large-scale, 

 low-density disordered network via a thermo-reversible gel transition. 

 By controlling the strand length, the gel transition temperature can be 

 made arbitrarily close to the percolation transition, in contrast with 

 recent model systems of physical gelation. This study helps the 

 understanding of self-assembly in this class of new biomaterials and 

 provides a bridge between physical and chemical gels.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ss06,

title = {Model for assembly and gelation of four-armed DNA dendrimers},

author = {Starr, Francis W. and Sciortino, Francesco},

url = {http://fstarr.web.wesleyan.edu/publications/ss.pdf},

doi = {10.1088/0953-8984/18/26/L02},

issn = {0953-8984},

year  = {2006},

date = {2006-07-01},

journal = {JOURNAL OF PHYSICS-CONDENSED MATTER},

volume = {18},

number = {26},

pages = {L347-L353},

abstract = {We introduce and numerically study a model designed to mimic the bulk behaviour of a system composed of single-stranded DNA dendrimers. Complementarity of the base sequences of different strands results in the formation of strong cooperative intermolecular links. We find that in an extremely narrow temperature range the system forms a large-scale, low-density disordered network via a thermo-reversible gel transition. By controlling the strand length, the gel transition temperature can be made arbitrarily close to the percolation transition, in contrast with recent model systems of physical gelation. This study helps the understanding of self-assembly in this class of new biomaterials and provides a bridge between physical and chemical gels.},

keywords = {Biophysics, DNA, Nanotechnology, Self Assembly},

pubstate = {published},

tppubtype = {article}

}

@article{mgss06b,

title = {Relation between rotational and translational dynamic heterogeneities in 

 water},

author = {MG Mazza and Nicolas Giovambattista and Francis W Starr and Eugene H Stanley},

url = {http://fstarr.web.wesleyan.edu/publications/mgss.pdf},

doi = {10.1103/PhysRevLett.96.057803},

issn = {0031-9007},

year  = {2006},

date = {2006-02-01},

journal = {PHYSICAL REVIEW LETTERS},

volume = {96},

number = {5},

pages = {057803},

abstract = {We use molecular dynamics simulations to probe the rotational dynamics 

 of the extended simple point charge model of water for a range of 

 temperatures down to 200 K, 6 K above the mode coupling temperature. We 

 find that rotational dynamics is spatially heterogeneous; i.e., there 

 are clusters of molecules that rotate significantly more than the 

 average for a given time interval, and we study the size and the 

 temporal behavior of these clusters. We find that the position of a 

 rotational heterogeneity is strongly correlated with the position of a 

 translational heterogeneity, and that the fraction of molecules 

 belonging to both kinds of heterogeneities increases with decreasing 

 temperature. We further find that although the two types of 

 heterogeneities are not identical, they are related to the same physical 

 picture.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{mgss06,

title = {Relation between rotational and translational dynamic heterogeneities in water},

author = {Mazza, MG and Giovambattista, Nicolas and Starr, Francis W. and Stanley, H. Eugene},

url = {http://fstarr.web.wesleyan.edu/publications/mgss.pdf},

doi = {10.1103/PhysRevLett.96.057803},

issn = {0031-9007},

year  = {2006},

date = {2006-02-01},

journal = {PHYSICAL REVIEW LETTERS},

volume = {96},

number = {5},

pages = {057803},

abstract = {We use molecular dynamics simulations to probe the rotational dynamics of the extended simple point charge model of water for a range of temperatures down to 200 K, 6 K above the mode coupling temperature. We find that rotational dynamics is spatially heterogeneous; i.e., there are clusters of molecules that rotate significantly more than the average for a given time interval, and we study the size and the temporal behavior of these clusters. We find that the position of a rotational heterogeneity is strongly correlated with the position of a translational heterogeneity, and that the fraction of molecules belonging to both kinds of heterogeneities increases with decreasing temperature. We further find that although the two types of heterogeneities are not identical, they are related to the same physical picture.},

keywords = {Dynamic Heterogeneity, Glass Formation, Water},

pubstate = {published},

tppubtype = {article}

}

@article{cswb,

title = {Weak correlations between local density and dynamics near the glass 

 transition},

author = {Jacinta C Conrad and Francis W Starr and David A Weitz},

url = {http://fstarr.web.wesleyan.edu/publications/csw.pdf},

doi = {10.1021/jp0514168},

issn = {1520-6106},

year  = {2005},

date = {2005-11-01},

journal = {JOURNAL OF PHYSICAL CHEMISTRY B},

volume = {109},

number = {45},

pages = {21235-21240},

abstract = {We perform experiments on two different dense colloidal suspensions with 

 confocal microscopy to probe the relationship between local structure 

 and dynamics near the glass transition. We calculate the Voronoi volume 

 19 for our particles and show that this quantity is not a universal 

 probe of glassy structure for all colloidal suspensions. We correlate 

 the Voronoi volume to displacement and find that these quantities are 

 only weakly correlated. We observe qualitatively similar results in a 

 simulation of a polymer melt. These results suggest that the Voronoi 

 volume does not predict dynamical behavior in experimental colloidal 

 suspensions; a purely 44 structural approach based on local single 

 particle volume likely cannot describe the colloidal glass transition.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kbsgs05b,

title = {Thermodynamics, structure, and dynamics of water confined between 

 hydrophobic plates},

author = {P Kumar and Sergey V Buldyrev and Francis W Starr and Nicolas Giovambattista and Eugene H Stanley},

url = {http://fstarr.web.wesleyan.edu/publications/kbsgs.pdf},

doi = {10.1103/PhysRevE.72.051503},

issn = {1539-3755},

year  = {2005},

date = {2005-11-01},

journal = {PHYSICAL REVIEW E},

volume = {72},

number = {5, 1},

pages = {051503},

abstract = {We perform molecular dynamics simulations of 512 waterlike molecules 

 that interact via the TIP5P potential and are confined between two 

 smooth hydrophobic plates that are separated by 1.10 nm. We find that 

 the anomalous thermodynamic properties of water are shifted to lower 

 temperatures relative to the bulk by approximate to 40 K. The dynamics 

 and structure of the confined water resemble bulk water at higher 

 temperatures, consistent with the shift of thermodynamic anomalies to 

 lower temperature. Because of this T shift, our confined water simulations (down to T=220 K) do not reach sufficiently low temperature 

 to observe a liquid-liquid phase transition found for bulk water at T 

 approximate to 215 K using the TIP5P potential, but we see inflections 

 in P-rho isotherms at lower temperatures presumably due to the presence 

 of a liquid-liquid critical point. We find that the different 

 crystalline structures that can form for two different separations of 

 the plates, 0.7 and 1.10 nm, have no counterparts in the bulk system, 

 and we discuss the relevance to experiments on confined water.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{csw,

title = {Weak correlations between local density and dynamics near the glass transition},

author = {Conrad, Jacinta C. and Starr, Francis W. and Weitz, David A.},

url = {http://fstarr.web.wesleyan.edu/publications/csw.pdf},

doi = {10.1021/jp0514168},

issn = {1520-6106},

year  = {2005},

date = {2005-11-01},

journal = {JOURNAL OF PHYSICAL CHEMISTRY B},

volume = {109},

number = {45},

pages = {21235-21240},

abstract = {We perform experiments on two different dense colloidal suspensions with confocal microscopy to probe the relationship between local structure and dynamics near the glass transition. We calculate the Voronoi volume 19 for our particles and show that this quantity is not a universal probe of glassy structure for all colloidal suspensions. We correlate the Voronoi volume to displacement and find that these quantities are only weakly correlated. We observe qualitatively similar results in a simulation of a polymer melt. These results suggest that the Voronoi volume does not predict dynamical behavior in experimental colloidal suspensions; a purely 44 structural approach based on local single particle volume likely cannot describe the colloidal glass transition.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kbsgs05,

title = {Thermodynamics, structure, and dynamics of water confined between hydrophobic plates},

author = {Kumar, P and Buldyrev, Sergey V. and Starr, Francis W. and Giovambattista, Nicolas and Stanley, H. Eugene},

url = {http://fstarr.web.wesleyan.edu/publications/kbsgs.pdf},

doi = {10.1103/PhysRevE.72.051503},

issn = {1539-3755},

year  = {2005},

date = {2005-11-01},

journal = {PHYSICAL REVIEW E},

volume = {72},

number = {5, 1},

pages = {051503},

abstract = {We perform molecular dynamics simulations of 512 waterlike molecules that interact via the TIP5P potential and are confined between two smooth hydrophobic plates that are separated by 1.10 nm. We find that the anomalous thermodynamic properties of water are shifted to lower temperatures relative to the bulk by approximate to 40 K. The dynamics and structure of the confined water resemble bulk water at higher temperatures, consistent with the shift of thermodynamic anomalies to lower temperature. Because of this T shift, our confined water simulations (down to T=220 K) do not reach sufficiently low temperature to observe a liquid-liquid phase transition found for bulk water at T approximate to 215 K using the TIP5P potential, but we see inflections in P-rho isotherms at lower temperatures presumably due to the presence of a liquid-liquid critical point. We find that the different crystalline structures that can form for two different separations of the plates, 0.7 and 1.10 nm, have no counterparts in the bulk system, and we discuss the relevance to experiments on confined water.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{gvbsg05b,

title = {Spatially heterogeneous dynamics and the Adam-Gibbs relation in the 

 Dzugutov liquid},

author = {Yeshitila Gebremichael and M Vogel and MNJ Bergroth and Francis W Starr and Sharon C Glotzer},

url = {http://fstarr.web.wesleyan.edu/publications/gvbsg.pdf},

doi = {10.1021/jp0512412},

issn = {1520-6106},

year  = {2005},

date = {2005-08-01},

journal = {JOURNAL OF PHYSICAL CHEMISTRY B},

volume = {109},

number = {31},

pages = {15068-15079},

abstract = {We perform molecular dynamics simulations of a one-component 

 glass-forming liquid and use the inherent structure formalism to test 

 the predictions of the Adam-Gibbs (AG) theory and to explore the 

 possible connection between these predictions and spatially 

 heterogeneous dynamics. We calculate the temperature dependence of the 

 average potential energy of the equilibrium liquid and show that it 

 obeys the Rosenfeld-Tarazona T-3/5 law for low temperature T, while the 

 average inherent structure energy is found to be inversely proportional 

 to temperature at low T, consistent with a Gaussian distribution of 

 potential energy minima. We investigate the shape of the basins around 

 the local minima in configuration space via the average basin 

 vibrational frequency and show that the basins become slightly broader 

 upon cooling. We evaluate the configurational entropy S-conf, a measure 

 of the multiplicity of potential energy minima sampled by the system, 

 and test the validity of the AG relation between S-conf and the bulk 

 dynamics. We quantify the dynamically heterogeneous motion by analyzing 

 the motion of particles that are mobile on short and intermediate time 

 scales relative to the characteristic bulk relaxation time. These mobile 

 particles move in one-dimensional ``strings'', and these strings form 

 clusters with a well-defined average cluster size. The AG approach 

 predicts that the minimum size of cooperatively rearranging regions 

 (CRR) of molecules is inversely proportional to Sconf, and recently 

 (Phys. Rev. Lett. 2003, 90, 085506) it has been shown that the 

 mobile-particle clusters are consistent with the CRR envisaged by Adam 

 and Gibbs. We test the possibility that the mobile-particle strings, 

 rather than clusters, may describe the CRR of the Adam-Gibbs approach. 

 We find that the strings also follow a nearly inverse relation with 

 S-conf. We further show that the logarithm of the time when the strings 

 and clusters are maximum, which occurs in the late-beta-relaxation 

 regime of the intermediate scattering function, follows a linear 

 relationship with 1/TSconf, in agreement with the AG prediction for the 

 relationship between the configurational entropy and the characteristic 

 time for the liquid to undergo a transition to a new configuration. 

 Since strings are the basic elements of the clusters, we propose that 

 strings are a more appropriate measure of the minimum size of a CRR that 

 leads to configurational transitions. That the cluster size also has an 

 inverse relationship with S-conf may be a consequence of the fact that 

 the clusters are composed of strings.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{gvbsg05,

title = {Spatially heterogeneous dynamics and the Adam-Gibbs relation in the Dzugutov liquid},

author = {Gebremichael, Yeshitila and Vogel, M and Bergroth, MNJ and Starr, Francis W. and Glotzer, Sharon C.},

url = {http://fstarr.web.wesleyan.edu/publications/gvbsg.pdf},

doi = {10.1021/jp0512412},

issn = {1520-6106},

year  = {2005},

date = {2005-08-01},

journal = {JOURNAL OF PHYSICAL CHEMISTRY B},

volume = {109},

number = {31},

pages = {15068-15079},

abstract = {We perform molecular dynamics simulations of a one-component glass-forming liquid and use the inherent structure formalism to test the predictions of the Adam-Gibbs (AG) theory and to explore the possible connection between these predictions and spatially heterogeneous dynamics. We calculate the temperature dependence of the average potential energy of the equilibrium liquid and show that it obeys the Rosenfeld-Tarazona T-3/5 law for low temperature T, while the average inherent structure energy is found to be inversely proportional to temperature at low T, consistent with a Gaussian distribution of potential energy minima. We investigate the shape of the basins around the local minima in configuration space via the average basin vibrational frequency and show that the basins become slightly broader upon cooling. We evaluate the configurational entropy S-conf, a measure of the multiplicity of potential energy minima sampled by the system, and test the validity of the AG relation between S-conf and the bulk dynamics. We quantify the dynamically heterogeneous motion by analyzing the motion of particles that are mobile on short and intermediate time scales relative to the characteristic bulk relaxation time. These mobile particles move in one-dimensional ``strings'', and these strings form clusters with a well-defined average cluster size. The AG approach predicts that the minimum size of cooperatively rearranging regions (CRR) of molecules is inversely proportional to Sconf, and recently (Phys. Rev. Lett. 2003, 90, 085506) it has been shown that the mobile-particle clusters are consistent with the CRR envisaged by Adam and Gibbs. We test the possibility that the mobile-particle strings, rather than clusters, may describe the CRR of the Adam-Gibbs approach. We find that the strings also follow a nearly inverse relation with S-conf. We further show that the logarithm of the time when the strings and clusters are maximum, which occurs in the late-beta-relaxation regime of the intermediate scattering function, follows a linear relationship with 1/TSconf, in agreement with the AG prediction for the relationship between the configurational entropy and the characteristic time for the liquid to undergo a transition to a new configuration. Since strings are the basic elements of the clusters, we propose that strings are a more appropriate measure of the minimum size of a CRR that leads to configurational transitions. That the cluster size also has an inverse relationship with S-conf may be a consequence of the fact that the clusters are composed of strings.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{gbss05b,

title = {Clusters of mobile molecules in supercooled water},

author = {Nicolas Giovambattista and Sergey V Buldyrev and Eugene H Stanley and Francis W Starr},

url = {http://fstarr.web.wesleyan.edu/publications/gbss-pre05.pdf},

doi = {10.1103/PhysRevE.72.011202},

issn = {1539-3755},

year  = {2005},

date = {2005-07-01},

journal = {PHYSICAL REVIEW E},

volume = {72},

number = {1, 1},

pages = {011202},

abstract = {We study the spatially heterogeneous dynamics in water via molecular 

 dynamics simulations using the extended simple point charge potential. 

 We identify clusters formed by mobile molecules and study their 

 properties. We find that these clusters grow in size and become more 

 compact as temperature decreases. We analyze the probability density 

 function of cluster size, and we study the cluster correlation length. 

 We find that clusters appear to be characterized by a fractal dimension 

 consistent with that of lattice animals. We relate the cluster size and 

 correlation length to the configurational entropy, S-conf. We find that 

 these quantities depend weakly on 1/S-conf. In particular, the linearity 

 found between the cluster mass n(*) and 1/S-conf suggests that n(*) 

 may be interpreted as the mass of the cooperatively rearranging regions 

 that form the basis of the Adam-Gibbs approach to the dynamics of 

 supercooled liquids. We study the motion of molecules within a cluster, 

 and find that each molecule preferentially follows a neighboring 

 molecule in the same cluster. Based on this finding we hypothesize that 

 stringlike cooperative motion may be a general mechanism for molecular 

 rearrangement of complex, as well as simple liquids. By mapping each 

 equilibrium configuration onto its corresponding local potential energy 

 minimum or inherent structure (IS), we are able to compare the mobile 

 molecule clusters in the equilibrium system with the molecules forming 

 the clusters identified in the transitions between IS. We find that (i) 

 mobile molecule clusters obtained by comparing different system 

 configurations and (ii) clusters obtained by comparing the corresponding 

 IS are completely different for short time scales, but are the same on 

 the longer time scales of diffusive motion.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{gbss05,

title = {Clusters of mobile molecules in supercooled water},

author = {Giovambattista, Nicolas and Buldyrev, Sergey V. and Stanley, H. Eugene and Starr, Francis W.},

url = {http://fstarr.web.wesleyan.edu/publications/gbss-pre05.pdf},

doi = {10.1103/PhysRevE.72.011202},

issn = {1539-3755},

year  = {2005},

date = {2005-07-01},

journal = {PHYSICAL REVIEW E},

volume = {72},

number = {1, 1},

pages = {011202},

abstract = {We study the spatially heterogeneous dynamics in water via molecular dynamics simulations using the extended simple point charge potential. We identify clusters formed by mobile molecules and study their properties. We find that these clusters grow in size and become more compact as temperature decreases. We analyze the probability density function of cluster size, and we study the cluster correlation length. We find that clusters appear to be characterized by a fractal dimension consistent with that of lattice animals. We relate the cluster size and correlation length to the configurational entropy, S-conf. We find that these quantities depend weakly on 1/S-conf. In particular, the linearity found between the cluster mass n(*) and 1/S-conf suggests that n(*) may be interpreted as the mass of the cooperatively rearranging regions that form the basis of the Adam-Gibbs approach to the dynamics of supercooled liquids. We study the motion of molecules within a cluster, and find that each molecule preferentially follows a neighboring molecule in the same cluster. Based on this finding we hypothesize that stringlike cooperative motion may be a general mechanism for molecular rearrangement of complex, as well as simple liquids. By mapping each equilibrium configuration onto its corresponding local potential energy minimum or inherent structure (IS), we are able to compare the mobile molecule clusters in the equilibrium system with the molecules forming the clusters identified in the transitions between IS. We find that (i) mobile molecule clusters obtained by comparing different system configurations and (ii) clusters obtained by comparing the corresponding IS are completely different for short time scales, but are the same on the longer time scales of diffusive motion.},

keywords = {Dynamic Heterogeneity, Glass Formation, Water},

pubstate = {published},

tppubtype = {article}

}

@article{sbfgs05b,

title = {Static and dynamic heterogeneities in water},

author = {Eugene H Stanley and Sergey V Buldyrev and Giancarlo Franzese and Nicolas Giovambattista and Francis W Starr},

url = {http://fstarr.web.wesleyan.edu/publications/sbfgs05.pdf},

doi = {10.1098/rspaaa.2004.1505},

issn = {1364-503X},

year  = {2005},

date = {2005-02-01},

journal = {PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL 

 AND ENGINEERING SCIENCES},

volume = {363},

number = {1827},

pages = {509-523},

abstract = {The thermodynamic behaviour of water seems to be related to static 

 heterogeneities. These static heterogeneities are related to the local 

 structure of water molecules and, when properly characterized, may offer 

 an economical explanation of thermodynamic data. `What matters' most in 

 determining some of the unusual properties of liquid water may be the 

 fact that the local geometry of the liquid molecules is not spherical or 

 oblong, but rather tetrahedral. In respect to static heterogeneities, 

 this local geometry is critical. The dynamic behaviour of water seems to 

 be related to dynamic heterogeneities, which seem to explain the 

 dynamics of supercooled liquid water well.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{sbfgs05,

title = {Static and dynamic heterogeneities in water},

author = {Stanley, H. Eugene and Buldyrev, Sergey V. and Franzese, Giancarlo and Giovambattista, Nicolas and Starr, Francis W.},

url = {http://fstarr.web.wesleyan.edu/publications/sbfgs05.pdf},

doi = {10.1098/rspaaa.2004.1505},

issn = {1364-503X},

year  = {2005},

date = {2005-02-01},

journal = {PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES},

volume = {363},

number = {1827},

pages = {509-523},

abstract = {The thermodynamic behaviour of water seems to be related to static heterogeneities. These static heterogeneities are related to the local structure of water molecules and, when properly characterized, may offer an economical explanation of thermodynamic data. `What matters' most in determining some of the unusual properties of liquid water may be the fact that the local geometry of the liquid molecules is not spherical or oblong, but rather tetrahedral. In respect to static heterogeneities, this local geometry is critical. The dynamic behaviour of water seems to be related to dynamic heterogeneities, which seem to explain the dynamics of supercooled liquid water well.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{gmbss04b,

title = {Dynamic heterogeneities in supercooled water},

author = {Nicolas Giovambattista and MG Mazza and Sergey V Buldyrev and Francis W Starr and Eugene H Stanley},

url = {http://fstarr.web.wesleyan.edu/publications/gmbss.pdf},

doi = {10.1021/jp037925w},

issn = {1520-6106},

year  = {2004},

date = {2004-05-01},

journal = {JOURNAL OF PHYSICAL CHEMISTRY B},

volume = {108},

number = {21},

pages = {6655-6662},

abstract = {We investigate dynamic heterogeneities in liquid water by performing 

 molecular dynamics simulations of the SPC/E model. We find clusters of 

 mobile molecules. We study the temperature and time dependence of the 

 cluster size and find that clusters grow as temperature decreases and 

 have a maximum size at the time scale corresponding to the escape of the 

 molecules from the cage formed by neighboring molecules. We relate the 

 average mass n* of mobile particle clusters to the diffusion constant, 

 D, and the configurational entropy, S-conf. We find that n* can be 

 interpreted as the mass of the ``cooperatively rearranging regions'' 

 hypothesized in the Adam-Gibbs theory of the dynamics of supercooled 

 liquids. In the context of the potential energy landscape (PEL) 

 approach, the diffusion of molecules is related to the change of basins. 

 By studying the dynamics of the system on the PEL, we identify clusters 

 formed by the molecules with large displacements as the system visits 

 consecutive local minima on the PEL. We relate the changing of basins 

 with the restructuring of the hydrogen bond network.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{gmbss04,

title = {Dynamic heterogeneities in supercooled water},

author = {Giovambattista, Nicolas and Mazza, MG and Buldyrev, Sergey V. and Starr, Francis W. and Stanley, H. Eugene},

url = {http://fstarr.web.wesleyan.edu/publications/gmbss.pdf},

doi = {10.1021/jp037925w},

issn = {1520-6106},

year  = {2004},

date = {2004-05-01},

journal = {JOURNAL OF PHYSICAL CHEMISTRY B},

volume = {108},

number = {21},

pages = {6655-6662},

abstract = {We investigate dynamic heterogeneities in liquid water by performing molecular dynamics simulations of the SPC/E model. We find clusters of mobile molecules. We study the temperature and time dependence of the cluster size and find that clusters grow as temperature decreases and have a maximum size at the time scale corresponding to the escape of the molecules from the cage formed by neighboring molecules. We relate the average mass n* of mobile particle clusters to the diffusion constant, D, and the configurational entropy, S-conf. We find that n* can be interpreted as the mass of the ``cooperatively rearranging regions'' hypothesized in the Adam-Gibbs theory of the dynamics of supercooled liquids. In the context of the potential energy landscape (PEL) approach, the diffusion of molecules is related to the change of basins. By studying the dynamics of the system on the PEL, we identify clusters formed by the molecules with large displacements as the system visits consecutive local minima on the PEL. We relate the changing of basins with the restructuring of the hydrogen bond network.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{lssg03b,

title = {Spatially heterogeneous dynamics investigated via a time-dependent 

 four-point density correlation function},

author = {Naida Lacevic and Francis W Starr and Thomas B Schrøder and Sharon C Glotzer},

url = {http://fstarr.web.wesleyan.edu/publications/lssg-jcp.pdf},

doi = {10.1063/1.1605094},

issn = {0021-9606},

year  = {2003},

date = {2003-10-01},

journal = {JOURNAL OF CHEMICAL PHYSICS},

volume = {119},

number = {14},

pages = {7372-7387},

abstract = {Relaxation in supercooled liquids above their glass transition and below 

 the onset temperature of ``slow'' dynamics involves the correlated 

 motion of neighboring particles. This correlated motion results in the 

 appearance of spatially heterogeneous dynamics or ``dynamical 

 heterogeneity.'' Traditional two-point time-dependent density 

 correlation functions, while providing information about the transient 

 ``caging'' of particles on cooling, are unable to provide sufficiently 

 detailed information about correlated motion and dynamical 

 heterogeneity. Here, we study a four-point, time-dependent density 

 correlation function g(4)(r,t) and corresponding ``structure factor'' 

 S(4)(q,t) which measure the spatial correlations between the local 

 liquid density at two points in space, each at two different times, and 

 so are sensitive to dynamical heterogeneity. We study g(4)(r,t) and 

 S(4)(q,t) via molecular dynamics simulations of a binary Lennard-Jones 

 mixture approaching the mode coupling temperature from above. We find 

 that the correlations between particles measured by g(4)(r,t) and 

 S(4)(q,t) become increasingly pronounced on cooling. The corresponding 

 dynamical correlation length xi(4)(t) extracted from the small-q 

 behavior of S(4)(q,t) provides an estimate of the range of correlated 

 particle motion. We find that xi(4)(t) has a maximum as a function of 

 time t, and that the value of the maximum of xi(4)(t) increases steadily 

 from less than one particle diameter to a value exceeding nine particle 

 diameters in the temperature range approaching the mode coupling 

 temperature from above. At the maximum, xi(4)(t) and the alpha 

 relaxation time tau(alpha) are related by a power law. We also examine 

 the individual contributions to g(4)(r,t), S(4)(q,t), and xi(4)(t), as 

 well as the corresponding order parameter Q(t) and generalized 

 susceptibility chi(4)(t), arising from the self and distinct 

 contributions to Q(t). These contributions elucidate key differences 

 between domains of localized and delocalized particles.(C) 2003 American 

 Institute of Physics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{lssg03,

title = {Spatially heterogeneous dynamics investigated via a time-dependent four-point density correlation function},

author = {Lacevic, Naida and Starr, Francis W. and Schrøder, Thomas B. and Glotzer, Sharon C.},

url = {http://fstarr.web.wesleyan.edu/publications/lssg-jcp.pdf},

doi = {10.1063/1.1605094},

issn = {0021-9606},

year  = {2003},

date = {2003-10-01},

journal = {JOURNAL OF CHEMICAL PHYSICS},

volume = {119},

number = {14},

pages = {7372-7387},

abstract = {Relaxation in supercooled liquids above their glass transition and below the onset temperature of ``slow'' dynamics involves the correlated motion of neighboring particles. This correlated motion results in the appearance of spatially heterogeneous dynamics or ``dynamical heterogeneity.'' Traditional two-point time-dependent density correlation functions, while providing information about the transient ``caging'' of particles on cooling, are unable to provide sufficiently detailed information about correlated motion and dynamical heterogeneity. Here, we study a four-point, time-dependent density correlation function g(4)(r,t) and corresponding ``structure factor'' S(4)(q,t) which measure the spatial correlations between the local liquid density at two points in space, each at two different times, and so are sensitive to dynamical heterogeneity. We study g(4)(r,t) and S(4)(q,t) via molecular dynamics simulations of a binary Lennard-Jones mixture approaching the mode coupling temperature from above. We find that the correlations between particles measured by g(4)(r,t) and S(4)(q,t) become increasingly pronounced on cooling. The corresponding dynamical correlation length xi(4)(t) extracted from the small-q behavior of S(4)(q,t) provides an estimate of the range of correlated particle motion. We find that xi(4)(t) has a maximum as a function of time t, and that the value of the maximum of xi(4)(t) increases steadily from less than one particle diameter to a value exceeding nine particle diameters in the temperature range approaching the mode coupling temperature from above. At the maximum, xi(4)(t) and the alpha relaxation time tau(alpha) are related by a power law. We also examine the individual contributions to g(4)(r,t), S(4)(q,t), and xi(4)(t), as well as the corresponding order parameter Q(t) and generalized susceptibility chi(4)(t), arising from the self and distinct contributions to Q(t). These contributions elucidate key differences between domains of localized and delocalized particles.(C) 2003 American Institute of Physics.},

keywords = {Dynamic Heterogeneity, Glass Formation},

pubstate = {published},

tppubtype = {article}

}

@article{agsbgb,

title = {Polymer-specific effects of bulk relaxation and stringlike correlated 

 motion in the dynamics of a supercooled polymer melt},

author = {Martin Aichele and Yeshitila Gebremichael and Francis W Starr and J Baschnagel and Sharon C Glotzer},

url = {http://fstarr.web.wesleyan.edu/publications/agsbg.pdf},

doi = {10.1063/1.1597473},

issn = {0021-9606},

year  = {2003},

date = {2003-09-01},

journal = {JOURNAL OF CHEMICAL PHYSICS},

volume = {119},

number = {10},

pages = {5290-5304},

abstract = {We analyze dynamical heterogeneities in a simulated ``bead-spring'' 

 model of a nonentangled, supercooled polymer melt. We explore the 

 importance of chain connectivity on the spatially heterogeneous motion 

 of the monomers. We find that when monomers move, they tend to follow 

 each other in one-dimensional paths, forming strings as previously 

 reported in atomic liquids and colloidal suspensions. The mean string 

 length is largest at a time close to the peak time of the mean cluster 

 size of mobile monomers. This maximum string length increases, roughly 

 in an exponential fashion, on cooling toward the critical temperature 

 T-MCT of the mode-coupling theory, but generally remains small, although 

 large strings involving ten or more monomers are observed. An important 

 contribution to this replacement comes from directly bonded neighbors in 

 the chain. However, mobility is not concentrated along the backbone of 

 the chains. Thus, a relaxation mechanism in which neighboring mobile 

 monomers along the chain move predominantly along the backbone of the 

 chains, seems unlikely for the system studied. (C) 2003 American 

 Institute of Physics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{salssss03b,

title = {Recent results on the connection between thermodynamics and dynamics in 

 supercooled water},

author = {Francis W Starr and Austen C Angell and Emilia La Nave and S Sastry and Antonio Scala and Francesco Sciortino and Eugene H Stanley},

url = {http://fstarr.web.wesleyan.edu/publications/salssss03.pdf},

doi = {10.1016/S0301-4622(03)00067-X},

issn = {0301-4622},

year  = {2003},

date = {2003-09-01},

journal = {BIOPHYSICAL CHEMISTRY},

volume = {105},

number = {2-3},

pages = {573-583},

abstract = {We review recent results on the connection between thermodynamics and 

 dynamics in a model for water. We verify the Adam-Gibbs relation between 

 entropy and dynamic properties using computer simulations, which allow 

 direct access to the relevant properties. We combine experimental 

 measurements of entropy with the Adam-Gibbs hypothesis to predict 

 dynamic properties in deeply supercooled states, which are difficult to 

 access experimentally. We find evidence suggesting that the glass 

 transition temperature of water may be significantly higher than 

 previously reported, but is still consistent with recent measurements. 

 Finally, we discuss the hypothesis that the dynamical behavior of deeply 

 supercooled water undergoes a crossover from `fragile' to `strong' 

 behavior. (C) 2003 Elsevier Science B.V All rights reserved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{agsbg,

title = {Polymer-specific effects of bulk relaxation and stringlike correlated motion in the dynamics of a supercooled polymer melt},

author = {Aichele, Martin and Gebremichael, Yeshitila and Starr, Francis W. and Baschnagel, J and Glotzer, Sharon C.},

url = {http://fstarr.web.wesleyan.edu/publications/agsbg.pdf},

doi = {10.1063/1.1597473},

issn = {0021-9606},

year  = {2003},

date = {2003-09-01},

journal = {JOURNAL OF CHEMICAL PHYSICS},

volume = {119},

number = {10},

pages = {5290-5304},

abstract = {We analyze dynamical heterogeneities in a simulated ``bead-spring'' model of a nonentangled, supercooled polymer melt. We explore the importance of chain connectivity on the spatially heterogeneous motion of the monomers. We find that when monomers move, they tend to follow each other in one-dimensional paths, forming strings as previously reported in atomic liquids and colloidal suspensions. The mean string length is largest at a time close to the peak time of the mean cluster size of mobile monomers. This maximum string length increases, roughly in an exponential fashion, on cooling toward the critical temperature T-MCT of the mode-coupling theory, but generally remains small, although large strings involving ten or more monomers are observed. An important contribution to this replacement comes from directly bonded neighbors in the chain. However, mobility is not concentrated along the backbone of the chains. Thus, a relaxation mechanism in which neighboring mobile monomers along the chain move predominantly along the backbone of the chains, seems unlikely for the system studied. (C) 2003 American Institute of Physics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{salssss03,

title = {Recent results on the connection between thermodynamics and dynamics in supercooled water},

author = {Starr, Francis W. and Angell, C. Austen and La Nave, Emilia and Sastry, S and Scala, Antonio and Sciortino, Francesco and Stanley, H. Eugene},

url = {http://fstarr.web.wesleyan.edu/publications/salssss03.pdf},

doi = {10.1016/S0301-4622(03)00067-X},

issn = {0301-4622},

year  = {2003},

date = {2003-09-01},

journal = {BIOPHYSICAL CHEMISTRY},

volume = {105},

number = {2-3},

pages = {573-583},

abstract = {We review recent results on the connection between thermodynamics and dynamics in a model for water. We verify the Adam-Gibbs relation between entropy and dynamic properties using computer simulations, which allow direct access to the relevant properties. We combine experimental measurements of entropy with the Adam-Gibbs hypothesis to predict dynamic properties in deeply supercooled states, which are difficult to access experimentally. We find evidence suggesting that the glass transition temperature of water may be significantly higher than previously reported, but is still consistent with recent measurements. Finally, we discuss the hypothesis that the dynamical behavior of deeply supercooled water undergoes a crossover from `fragile' to `strong' behavior. (C) 2003 Elsevier Science B.V All rights reserved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{sdg03b,

title = {Origin of particle clustering in a simulated polymer nanocomposite and 

 its impact on rheology},

author = {Francis W Starr and Jack F Douglas and Sharon C Glotzer},

url = {http://fstarr.web.wesleyan.edu/publications/sdg.pdf},

doi = {10.1063/1.1580099},

issn = {0021-9606},

year  = {2003},

date = {2003-07-01},

journal = {JOURNAL OF CHEMICAL PHYSICS},

volume = {119},

number = {3},

pages = {1777-1788},

abstract = {Many nanoparticles have short-range interactions relative to their size, 

 and these interactions tend to be ``patchy'' since the interatomic 

 spacing is comparable to the nanoparticle size. For a dispersion of such 

 particles, it is not a priori obvious what mechanism will control the 

 clustering of the nanoparticles, and how the clustering will be affected 

 by tuning various control parameters. To gain insight into these 

 questions, we perform molecular dynamics simulations of polyhedral 

 nanoparticles in a dense bead-spring polymer melt under both quiescent 

 and steady shear conditions. We explore the mechanism that controls 

 nanoparticle clustering and find that the crossover from dispersed to 

 clustered states is consistent with the predictions for equilibrium 

 particle association or equilibrium polymerization, and that the 

 crossover does not appear to match the expectations for first-order 

 phase separation typical for binary mixtures in the region of the phase 

 diagram where we can equilibrate the system. At the same time, we cannot 

 rule out the possibility of phase separation at a lower temperature. 

 Utilizing the existing framework for dynamic clustering transitions 

 offers the possibility of more rationally controlling the dispersion and 

 properties of nanocomposite materials. Finally, we examine how 

 nanocomposite rheology depends on the state of equilibrium clustering. 

 We find that the shear viscosity for dispersed configurations is larger 

 than that for clustered configurations, in contrast to expectations 

 based on macroscopic colloidal dispersions. We explain this result by 

 the alteration of the polymer matrix properties in the vicinity of the 

 nanoparticles. We also show that shear tends to disperse clustered 

 nanoparticle configurations in our system, an effect particularly 

 important for processing. (C) 2003 American Institute of Physics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{sdg03,

title = {Origin of particle clustering in a simulated polymer nanocomposite and its impact on rheology},

author = {Starr, Francis W. and Douglas, Jack F. and Glotzer, Sharon C.},

url = {http://fstarr.web.wesleyan.edu/publications/sdg.pdf},

doi = {10.1063/1.1580099},

issn = {0021-9606},

year  = {2003},

date = {2003-07-01},

journal = {JOURNAL OF CHEMICAL PHYSICS},

volume = {119},

number = {3},

pages = {1777-1788},

abstract = {Many nanoparticles have short-range interactions relative to their size, and these interactions tend to be ``patchy'' since the interatomic spacing is comparable to the nanoparticle size. For a dispersion of such particles, it is not a priori obvious what mechanism will control the clustering of the nanoparticles, and how the clustering will be affected by tuning various control parameters. To gain insight into these questions, we perform molecular dynamics simulations of polyhedral nanoparticles in a dense bead-spring polymer melt under both quiescent and steady shear conditions. We explore the mechanism that controls nanoparticle clustering and find that the crossover from dispersed to clustered states is consistent with the predictions for equilibrium particle association or equilibrium polymerization, and that the crossover does not appear to match the expectations for first-order phase separation typical for binary mixtures in the region of the phase diagram where we can equilibrate the system. At the same time, we cannot rule out the possibility of phase separation at a lower temperature. Utilizing the existing framework for dynamic clustering transitions offers the possibility of more rationally controlling the dispersion and properties of nanocomposite materials. Finally, we examine how nanocomposite rheology depends on the state of equilibrium clustering. We find that the shear viscosity for dispersed configurations is larger than that for clustered configurations, in contrast to expectations based on macroscopic colloidal dispersions. We explain this result by the alteration of the polymer matrix properties in the vicinity of the nanoparticles. We also show that shear tends to disperse clustered nanoparticle configurations in our system, an effect particularly important for processing. (C) 2003 American Institute of Physics.},

keywords = {Nanocomposites, Polymers, Self Assembly},

pubstate = {published},

tppubtype = {article}

}

@article{sas03b,

title = {Prediction of entropy and dynamic properties of water below the 

 homogeneous nucleation temperature},

author = {Francis W Starr and Austen C Angell and Eugene H Stanley},

url = {http://fstarr.web.wesleyan.edu/publications/sas.pdf},

doi = {10.1016/S0378-4371(03)00012-8},

issn = {0378-4371},

year  = {2003},

date = {2003-05-01},

journal = {PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS},

volume = {323},

pages = {51-66},

abstract = {The behavior of thermodynamic and dynamic properties of liquid water at 

 atmospheric pressure in the temperature range between the lower limit of 

 supercooling (T-H approximate to 235 K) and the onset of the glassy 

 state at T-g has been the focus of much research, and many questions 

 remain about the properties of water in this region. Since direct 

 measurements on water in this temperature range remain largely 

 infeasible, we use existing experimental measurements of the entropy, 

 specific heat, and enthalpy outside this range to construct a possible 

 form of the entropy in the ``difficult-to-probe'' region. Assuming 

 that the entropy is well-defined in extreme metastable states, and that 

 there is no intervening discontinuity at atmospheric pressure, we 

 estimate the excess entropy S-ex of the liquid over the crystal within 

 relatively narrow limits. We find that our approximate form for S-ex 

 shows atypical behavior when compared with other liquids: using a 

 thermodynamic categorization of ``strong'' and ``fragile'' liquids, 

 water appears to be fragile on initial cooling below the melting 

 temperature, and strong in the temperature region near the glass 

 transition. This thermodynamic construction can be used, with 

 appropriate reservations, to estimate the behavior of the dynamic 

 properties of water by means of the Adam-Gibbs equation-which relates 

 configurational entropy S-conf to dynamic behavior. Although the 

 Adam-Gibbs equation uses S-conf rather than S-ex as the control 

 variable, the relation has been used successfully in a number of 

 experimental studies with S-conf replaced by S-ex. This is likely a 

 result of a proportionality between S-conf and S-ex, which we confirm 

 for simulations of a model of water. Hence by using the constructed 

 values of S-ex, together with experimental data in the range where S-ex 

 is known, we estimate the temperature dependence of viscosity and 

 diffusivity approaching the glass transition. Like the entropy plots, 

 Arrhenius plots of viscosity or diffusion show an inflection, implying a 

 crossover from fragile to strong liquid character below T-H. The 

 dynamics results also imply T-g approximate to 160 K, which is 

 considerably above the expected value of 136 K from older experiments, 

 but consistent with other recent evidence based on hyperquenched glass 

 properties. We discuss the possibility of experimentally verifying our 

 predictions, and briefly discuss other liquids that also may follow a 

 strong-to-fragile pattern. (C) 2003 Elsevier Science B.V. All rights 

 reserved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{sas03,

title = {Prediction of entropy and dynamic properties of water below the homogeneous nucleation temperature},

author = {Starr, Francis W. and Angell, C. Austen and Stanley, H. Eugene},

url = {http://fstarr.web.wesleyan.edu/publications/sas.pdf},

doi = {10.1016/S0378-4371(03)00012-8},

issn = {0378-4371},

year  = {2003},

date = {2003-05-01},

journal = {PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS},

volume = {323},

pages = {51-66},

abstract = {The behavior of thermodynamic and dynamic properties of liquid water at atmospheric pressure in the temperature range between the lower limit of supercooling (T-H approximate to 235 K) and the onset of the glassy state at T-g has been the focus of much research, and many questions remain about the properties of water in this region. Since direct measurements on water in this temperature range remain largely infeasible, we use existing experimental measurements of the entropy, specific heat, and enthalpy outside this range to construct a possible form of the entropy in the ``difficult-to-probe'' region. Assuming that the entropy is well-defined in extreme metastable states, and that there is no intervening discontinuity at atmospheric pressure, we estimate the excess entropy S-ex of the liquid over the crystal within relatively narrow limits. We find that our approximate form for S-ex shows atypical behavior when compared with other liquids: using a thermodynamic categorization of ``strong'' and ``fragile'' liquids, water appears to be fragile on initial cooling below the melting temperature, and strong in the temperature region near the glass transition. This thermodynamic construction can be used, with appropriate reservations, to estimate the behavior of the dynamic properties of water by means of the Adam-Gibbs equation-which relates configurational entropy S-conf to dynamic behavior. Although the Adam-Gibbs equation uses S-conf rather than S-ex as the control variable, the relation has been used successfully in a number of experimental studies with S-conf replaced by S-ex. This is likely a result of a proportionality between S-conf and S-ex, which we confirm for simulations of a model of water. Hence by using the constructed values of S-ex, together with experimental data in the range where S-ex is known, we estimate the temperature dependence of viscosity and diffusivity approaching the glass transition. Like the entropy plots, Arrhenius plots of viscosity or diffusion show an inflection, implying a crossover from fragile to strong liquid character below T-H. The dynamics results also imply T-g approximate to 160 K, which is considerably above the expected value of 136 K from older experiments, but consistent with other recent evidence based on hyperquenched glass properties. We discuss the possibility of experimentally verifying our predictions, and briefly discuss other liquids that also may follow a strong-to-fragile pattern. (C) 2003 Elsevier Science B.V. All rights reserved.},

keywords = {Glass Formation, Polyamorphism, Water},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000180701300027b,

title = {Application of statistical physics to understand static and dynamic 

 anomalies in liquid water},

author = {Eugene H Stanley and Sergey V Buldyrev and Nicolas Giovambattista and Emilia La Nave and Stefano Mossa and Antonio Scala and Francesco Sciortino and Francis W Starr and Masako Yamada},

doi = {10.1023/A:1022188608924},

issn = {0022-4715},

year  = {2003},

date = {2003-03-01},

journal = {JOURNAL OF STATISTICAL PHYSICS},

volume = {110},

number = {3-6},

pages = {1039-1054},

abstract = {We present an overview of recent research applying ideas of statistical 

 mechanics to try to better understand the statics and especially the 

 dynamic puzzles regarding liquid water. We discuss recent molecular 

 dynamics simulations using the Mahoney- Jorgensen transferable 

 intermolecular potential with five points (TIP5P), which is closer to 

 real water than previously-proposed classical pairwise additive 

 potentials. Simulations of the TIP5P model for a wide range of deeply 

 supercooled states, including both positive and negative pressures, 

 reveal (i) the existence of a non-monotonic temperature of maximum 

 density line and a non-reentrant spinodal, (ii) the presence of a 

 low-temperature phase transition. The take-home message for the static 

 aspects is that what seems to ``matter'' more than previously 

 appreciated is local tetrahedral order, so that liquid water has 

 features in common with SiO(2) and P, as well as perhaps Si and C. To 

 better understand dynamic aspects of water, we focus on the role of the 

 number of diffusive directions in the potential energy landscape. What 

 seems to ``matter'' most is not values of thermodynamic parameters 

 such as temperature T and pressure P, but only the value of a parameter 

 characterizing the potential energy landscape-just as near a critical 

 point what matters is not the values of T and P but rather the values of 

 the correlation length.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000180701300027,

title = {Application of statistical physics to understand static and dynamic anomalies in liquid water},

author = {Stanley, H. Eugene and Buldyrev, Sergey V. and Giovambattista, Nicolas and La Nave, Emilia and Mossa, Stefano and Scala, Antonio and Sciortino, Francesco and Starr, Francis W. and Yamada, Masako},

doi = {10.1023/A:1022188608924},

issn = {0022-4715},

year  = {2003},

date = {2003-03-01},

journal = {JOURNAL OF STATISTICAL PHYSICS},

volume = {110},

number = {3-6},

pages = {1039-1054},

abstract = {We present an overview of recent research applying ideas of statistical mechanics to try to better understand the statics and especially the dynamic puzzles regarding liquid water. We discuss recent molecular dynamics simulations using the Mahoney- Jorgensen transferable intermolecular potential with five points (TIP5P), which is closer to real water than previously-proposed classical pairwise additive potentials. Simulations of the TIP5P model for a wide range of deeply supercooled states, including both positive and negative pressures, reveal (i) the existence of a non-monotonic temperature of maximum density line and a non-reentrant spinodal, (ii) the presence of a low-temperature phase transition. The take-home message for the static aspects is that what seems to ``matter'' more than previously appreciated is local tetrahedral order, so that liquid water has features in common with SiO(2) and P, as well as perhaps Si and C. To better understand dynamic aspects of water, we focus on the role of the number of diffusive directions in the potential energy landscape. What seems to ``matter'' most is not values of thermodynamic parameters such as temperature T and pressure P, but only the value of a parameter characterizing the potential energy landscape-just as near a critical point what matters is not the values of T and P but rather the values of the correlation length.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{gbss03b,

title = {Connection between Adam-Gibbs theory and spatially heterogeneous 

 dynamics},

author = {Nicolas Giovambattista and Sergey V Buldyrev and Francis W Starr and Eugene H Stanley},

url = {http://fstarr.web.wesleyan.edu/publications/gbss.pdf},

doi = {10.1103/PhysRevLett.90.085506},

issn = {0031-9007},

year  = {2003},

date = {2003-02-01},

journal = {PHYSICAL REVIEW LETTERS},

volume = {90},

number = {8},

pages = {085506},

abstract = {We investigate the spatially heterogeneous dynamics in the extended 

 simple point charge model of water using molecular dynamics simulations. 

 We relate the average mass n(*) of mobile particle clusters to the 

 diffusion constant and the configurational entropy. Hence, n(*) can be 

 interpreted as the mass of the ``cooperatively rearranging regions'' 

 that form the basis of the Adam-Gibbs theory of the dynamics of 

 supercooled liquids. We also examine the time and temperature dependence 

 of these transient clusters.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{gbss03,

title = {Connection between Adam-Gibbs theory and spatially heterogeneous dynamics},

author = {Giovambattista, Nicolas and Buldyrev, Sergey V. and Starr, Francis W. and Stanley, H. Eugene},

url = {http://fstarr.web.wesleyan.edu/publications/gbss.pdf},

doi = {10.1103/PhysRevLett.90.085506},

issn = {0031-9007},

year  = {2003},

date = {2003-02-01},

journal = {PHYSICAL REVIEW LETTERS},

volume = {90},

number = {8},

pages = {085506},

abstract = {We investigate the spatially heterogeneous dynamics in the extended simple point charge model of water using molecular dynamics simulations. We relate the average mass n(*) of mobile particle clusters to the diffusion constant and the configurational entropy. Hence, n(*) can be interpreted as the mass of the ``cooperatively rearranging regions'' that form the basis of the Adam-Gibbs theory of the dynamics of supercooled liquids. We also examine the time and temperature dependence of these transient clusters.},

keywords = {Dynamic Heterogeneity, Glass Formation, Water},

pubstate = {published},

tppubtype = {article}

}

@article{slsss02b,

title = {Water and its energy landscape},

author = {Francesco Sciortino and Emilia La Nave and Antonio Scala and Eugene H Stanley and Francis W Starr},

doi = {10.1140/epje/i2002-10080-6},

issn = {1292-8941},

year  = {2002},

date = {2002-11-01},

journal = {EUROPEAN PHYSICAL JOURNAL E},

volume = {9},

number = {3},

pages = {233-237},

abstract = {We present an overview of the recent studies on the properties of the 

 potential energy surface for a simple model of water. We emphasize the 

 relations between PES properties and dynamics in supercooled states for 

 the model and discuss possible future application of the PES studies.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nsbsb,

title = {Translational and rotational diffusion in stretched water},

author = {Paulo A Netz and Francis Starr and Marcia C Barbosa and Eugene H Stanley},

url = {http://fstarr.web.wesleyan.edu/publications/nsbs.pdf},

doi = {10.1016/S0167-7322(02)00090-9},

issn = {0167-7322},

year  = {2002},

date = {2002-11-01},

journal = {JOURNAL OF MOLECULAR LIQUIDS},

volume = {101},

number = {1-3},

pages = {159-168},

abstract = {We perform molecular dynamics simulations using the extended simple 

 point charge SPC/E water model in order to investigate the dynamical 

 behavior of supercooled-stretched water. We focus on the behavior of the 

 translational diffusion coefficient, the orientational relaxation time, 

 and the local hydrogen bond network. Decreasing density or pressure 

 along an isothermal path, there is a mininum in the diffusion 

 coefficient and a maximum in the orientational relaxation time, 

 suggesting an initial enhancement and subsequent breakdown of the 

 tetrahedral structure and of the hydrogen bond network as the density 

 decreases. The analysis of the tetrahedral structure of the nearest 

 neighbors help to clarify the relationship between the local structural 

 changes and the system dynamics We also find that the product of 

 diffusion coefficient and relaxation time is nearly constant. indicating 

 that the anomalous behavior observed in the rotational and translational 

 diffusion arise from the same microscopic mechanism. (C) 2002 Elsevier 

 Science B.V. All rights reserved.},

note = {EuroConference on Molecular Liquids, OBERNAI, FRANCE, SEP 07-12, 2001},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000179502800064b,

title = {Relation between structural and dynamical anomalies in supercooled water},

author = {PA Netz and Francis W Starr and MC Barbosa and Eugene H Stanley},

url = {http://fstarr.web.wesleyan.edu/publications/},

doi = {10.1016/S0378-4371(02)01083-X},

issn = {0378-4371},

year  = {2002},

date = {2002-11-01},

journal = {PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS},

volume = {314},

number = {1-4},

pages = {470-476},

abstract = {We step toward the elucidation of the relation between the structural 

 and dynamic anomalies in supercooled water. We present the results of 

 molecular dynamics simulations of the extended simple point charge 

 (SPC/E) model of water for the translational and rotational diffusion 

 and for the number of neighbors and hydrogen bonds. We find that the 

 product of diffusion coefficient and relaxation time is nearly constant. 

 The coupling between the two mobilities is explained in the framework of 

 the structural anomalies. (C) 2002 Elsevier Science B.V. All rights 

 reserved.},

note = {Meeting on Horizons in Complex Systems, MESSINA, ITALY, DEC, 2001},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{slsss02,

title = {Water and its energy landscape},

author = {Sciortino, Francesco and La Nave, Emilia and Scala, Antonio and Stanley, H. Eugene and Starr, Francis W.},

doi = {10.1140/epje/i2002-10080-6},

issn = {1292-8941},

year  = {2002},

date = {2002-11-01},

journal = {EUROPEAN PHYSICAL JOURNAL E},

volume = {9},

number = {3},

pages = {233-237},

abstract = {We present an overview of the recent studies on the properties of the potential energy surface for a simple model of water. We emphasize the relations between PES properties and dynamics in supercooled states for the model and discuss possible future application of the PES studies.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nsbs,

title = {Translational and rotational diffusion in stretched water},

author = {Netz, Paulo A and Starr, Francis and Barbosa, Marcia C. and Stanley, H. Eugene},

url = {http://fstarr.web.wesleyan.edu/publications/nsbs.pdf},

doi = {10.1016/S0167-7322(02)00090-9},

issn = {0167-7322},

year  = {2002},

date = {2002-11-01},

journal = {JOURNAL OF MOLECULAR LIQUIDS},

volume = {101},

number = {1-3},

pages = {159-168},

abstract = {We perform molecular dynamics simulations using the extended simple point charge SPC/E water model in order to investigate the dynamical behavior of supercooled-stretched water. We focus on the behavior of the translational diffusion coefficient, the orientational relaxation time, and the local hydrogen bond network. Decreasing density or pressure along an isothermal path, there is a mininum in the diffusion coefficient and a maximum in the orientational relaxation time, suggesting an initial enhancement and subsequent breakdown of the tetrahedral structure and of the hydrogen bond network as the density decreases. The analysis of the tetrahedral structure of the nearest neighbors help to clarify the relationship between the local structural changes and the system dynamics We also find that the product of diffusion coefficient and relaxation time is nearly constant. indicating that the anomalous behavior observed in the rotational and translational diffusion arise from the same microscopic mechanism. (C) 2002 Elsevier Science B.V. All rights reserved.},

note = {EuroConference on Molecular Liquids, OBERNAI, FRANCE, SEP 07-12, 2001},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000179502800064,

title = {Relation between structural and dynamical anomalies in supercooled water},

author = {Netz, PA and Starr, Francis W. and Barbosa, MC and Stanley, H. Eugene},

url = {http://fstarr.web.wesleyan.edu/publications/},

doi = {10.1016/S0378-4371(02)01083-X},

issn = {0378-4371},

year  = {2002},

date = {2002-11-01},

journal = {PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS},

volume = {314},

number = {1-4},

pages = {470-476},

abstract = {We step toward the elucidation of the relation between the structural and dynamic anomalies in supercooled water. We present the results of molecular dynamics simulations of the extended simple point charge (SPC/E) model of water for the translational and rotational diffusion and for the number of neighbors and hydrogen bonds. We find that the product of diffusion coefficient and relaxation time is nearly constant. The coupling between the two mobilities is explained in the framework of the structural anomalies. (C) 2002 Elsevier Science B.V. All rights reserved.},

note = {Meeting on Horizons in Complex Systems, MESSINA, ITALY, DEC, 2001},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000178166900022b,

title = {What do we learn from the local geometry of glass-forming liquids?},

author = {Francis W Starr and S Sastry and Jack F Douglas and Sharon C Glotzer},

url = {http://fstarr.web.wesleyan.edu/publications/ssdg.pdf},

doi = {10.1103/PhysRevLett.89.125501},

issn = {0031-9007},

year  = {2002},

date = {2002-09-01},

journal = {PHYSICAL REVIEW LETTERS},

volume = {89},

number = {12},

pages = {125501},

abstract = {We examine the local geometry of a simulated glass-forming polymer melt. 

 Using the Voronoi construction, we find that the distributions of 

 Voronoi volume P(u(v)) and asphericity P(a) appear to be universal 

 properties of dense liquids, supporting the use of packing approaches to 

 understand liquid properties. We also calculate the average free volume 

 [u(f)] along a path of constant density and find that [u(f)] 

 extrapolates to zero at the same temperature T-0 that the extrapolated 

 relaxation time diverges. We relate [u(f)] to the Debye-Waller factor, 

 which is measurable by neutron scattering.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000178623300001b,

title = {Growing correlation length on cooling below the onset of caging in a 

 simulated glass-forming liquid},

author = {Naida Lacevic and Francis W Starr and Thomas B Schrøder and VN Novikov and Sharon C Glotzer},

url = {http://fstarr.web.wesleyan.edu/publications/},

doi = {10.1103/PhysRevE.66.030101},

issn = {1539-3755},

year  = {2002},

date = {2002-09-01},

journal = {PHYSICAL REVIEW E},

volume = {66},

number = {3, 1},

pages = {030101},

abstract = {We present a calculation of a fourth-order, time-dependent density 

 correlation function that measures higher-order spatiotemporal 

 correlations of the density of a liquid. From molecular dynamics 

 simulations of a glass-forming Lennard-Jones liquid, we find that the 

 characteristic length scale of this function has a maximum as a function 

 of time which increases steadily beyond the characteristic length of the 

 static pair correlation function g(r) in the temperature range 

 approaching the mode coupling temperature from above. This length scale 

 provides a measure of the spatially heterogeneous nature of the dynamics 

 of the liquid in the alpha-relaxation regime.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000178166900022,

title = {What do we learn from the local geometry of glass-forming liquids?},

author = {Starr, Francis W. and Sastry, S and Douglas, Jack F. and Glotzer, Sharon C.},

url = {http://fstarr.web.wesleyan.edu/publications/ssdg.pdf},

doi = {10.1103/PhysRevLett.89.125501},

issn = {0031-9007},

year  = {2002},

date = {2002-09-01},

journal = {PHYSICAL REVIEW LETTERS},

volume = {89},

number = {12},

pages = {125501},

abstract = {We examine the local geometry of a simulated glass-forming polymer melt. Using the Voronoi construction, we find that the distributions of Voronoi volume P(u(v)) and asphericity P(a) appear to be universal properties of dense liquids, supporting the use of packing approaches to understand liquid properties. We also calculate the average free volume [u(f)] along a path of constant density and find that [u(f)] extrapolates to zero at the same temperature T-0 that the extrapolated relaxation time diverges. We relate [u(f)] to the Debye-Waller factor, which is measurable by neutron scattering.},

keywords = {Glass Formation},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000178623300001,

title = {Growing correlation length on cooling below the onset of caging in a simulated glass-forming liquid},

author = {Lacevic, Naida and Starr, Francis W. and Schrøder, Thomas B. and Novikov, VN and Glotzer, Sharon C.},

url = {http://fstarr.web.wesleyan.edu/publications/},

doi = {10.1103/PhysRevE.66.030101},

issn = {1539-3755},

year  = {2002},

date = {2002-09-01},

journal = {PHYSICAL REVIEW E},

volume = {66},

number = {3, 1},

pages = {030101},

abstract = {We present a calculation of a fourth-order, time-dependent density correlation function that measures higher-order spatiotemporal correlations of the density of a liquid. From molecular dynamics simulations of a glass-forming Lennard-Jones liquid, we find that the characteristic length scale of this function has a maximum as a function of time which increases steadily beyond the characteristic length of the static pair correlation function g(r) in the temperature range approaching the mode coupling temperature from above. This length scale provides a measure of the spatially heterogeneous nature of the dynamics of the liquid in the alpha-relaxation regime.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000176373900005b,

title = {Glass-forming liquids and polymers: with a little help from 

 computational statistical physics},

author = {Sharon C Glotzer and Yeshitila Gebremichael and Naida Lacevic and Thomas B Schrøder and Francis W Starr},

url = {http://fstarr.web.wesleyan.edu/publications/},

doi = {10.1016/S0010-4655(02)00431-9},

issn = {0010-4655},

year  = {2002},

date = {2002-06-01},

journal = {COMPUTER PHYSICS COMMUNICATIONS},

volume = {146},

number = {1},

pages = {24-29},

note = {International Conference on Statistical Physics, ATHENS, GEORGIA, JUL 

 23-25, 2001},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000176373900005,

title = {Glass-forming liquids and polymers: with a little help from computational statistical physics},

author = {Glotzer, Sharon C. and Gebremichael, Yeshitila and Lacevic, Naida and Schrøder, Thomas B. and Starr, Francis W.},

url = {http://fstarr.web.wesleyan.edu/publications/},

doi = {10.1016/S0010-4655(02)00431-9},

issn = {0010-4655},

year  = {2002},

date = {2002-06-01},

journal = {COMPUTER PHYSICS COMMUNICATIONS},

volume = {146},

number = {1},

pages = {24-29},

note = {International Conference on Statistical Physics, ATHENS, GEORGIA, JUL 23-25, 2001},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000175728100037b,

title = {Molecular dynamics simulation of a polymer melt with a nanoscopic 

 particle},

author = {Francis W Starr and Thomas B Schrøder and Sharon C Glotzer},

url = {http://fstarr.web.wesleyan.edu/publications/ssg-mmol.pdf},

doi = {10.1021/ma010626p},

issn = {0024-9297},

year  = {2002},

date = {2002-05-01},

journal = {MACROMOLECULES},

volume = {35},

number = {11},

pages = {4481-4492},

abstract = {We perform molecular dynamics simulations of a bead-spring polymer melt 

 surrounding a nanoscopic particle. We explore the effect of the 

 polymer/nanoparticle interactions, surface-to-volume ratio, and boundary 

 conditions on both the structure and dynamics of the polymer melt. We 

 find that the chains near the nanoparticle surface are elongated and 

 flattened and that this effect is independent of the interaction for the 

 range of interactions we study. We show that the glass transition 

 temperature T-g of the melt can be shifted to either higher or lower 

 temperatures by tuning the interactions between polymer and 

 nanoparticle. A gradual change of the polymer dynamics approaching the 

 nanoparticle surface causes the change in the glass transition. The 

 magnitude of the shift is exaggerated by increasing fraction of surface 

 monomers in the system. These behaviors support a ``many-layer''-based 

 interpretation of the dynamics. Our findings appear applicable to 

 systems in which surface interactions dominate, including both 

 traditional and nanofilled polymer melts, as well as systems with 

 markedly different geometries, such as ultrathin polymer films. In 

 particular, we show how our results might be compared with those 

 obtained from experimental studies of ``bound'' polymer.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000175728100037,

title = {Molecular dynamics simulation of a polymer melt with a nanoscopic particle},

author = {Starr, Francis W. and Schrøder, Thomas B. and Glotzer, Sharon C.},

url = {http://fstarr.web.wesleyan.edu/publications/ssg-mmol.pdf},

doi = {10.1021/ma010626p},

issn = {0024-9297},

year  = {2002},

date = {2002-05-01},

journal = {MACROMOLECULES},

volume = {35},

number = {11},

pages = {4481-4492},

abstract = {We perform molecular dynamics simulations of a bead-spring polymer melt surrounding a nanoscopic particle. We explore the effect of the polymer/nanoparticle interactions, surface-to-volume ratio, and boundary conditions on both the structure and dynamics of the polymer melt. We find that the chains near the nanoparticle surface are elongated and flattened and that this effect is independent of the interaction for the range of interactions we study. We show that the glass transition temperature T-g of the melt can be shifted to either higher or lower temperatures by tuning the interactions between polymer and nanoparticle. A gradual change of the polymer dynamics approaching the nanoparticle surface causes the change in the glass transition. The magnitude of the shift is exaggerated by increasing fraction of surface monomers in the system. These behaviors support a ``many-layer''-based interpretation of the dynamics. Our findings appear applicable to systems in which surface interactions dominate, including both traditional and nanofilled polymer melts, as well as systems with markedly different geometries, such as ultrathin polymer films. In particular, we show how our results might be compared with those obtained from experimental studies of ``bound'' polymer.},

keywords = {Glass Formation, Nanocomposites, Polymers},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000175781700025b,

title = {Statistical physics and liquid water: ``What matters''},

author = {Eugene H Stanley and Sergey V Buldyrev and Nicolas Giovambattista and Emilia La Nave and Antonio Scala and Francesco Sciortino and Francis W Starr},

url = {http://fstarr.web.wesleyan.edu/publications/},

doi = {10.1016/S0378-4371(02)00544-7},

issn = {0378-4371},

year  = {2002},

date = {2002-04-01},

journal = {PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS},

volume = {306},

number = {1-4},

pages = {230-242},

abstract = {We present an over-view of recent research applying ideas of statistical 

 mechanics to try to better understand the statics and especially the 

 dynamic puzzles regarding liquid water. The take-home message for the 

 static aspects is that what seems to ``matter'' more than previously 

 appreciated is local tetrahedral order, so that liquid water has 

 features in common with SiO(2) and P, as well as perhaps Si and C. For 

 the dynamic aspects, what may ``matter'' is the number of diffusive 

 directions in the potential energy landscape. (C) 2002 Published by 

 Elsevier Science B.V.},

note = {21st IUPAP International Conference on Statistical Physics, CANCUN, 

 MEXICO, JUL 15-21, 2001},

keywords = {},

pubstate = {published},

tppubtype = {article}

}