Publications by year, excluding conference proceedings.
Complete CV Google Scholar Page
2017
Giovambattista, Nicolas; Starr, Francis W.; Poole, Peter H.
Influence of sample preparation on the transformation of low-density to high-density amorphous ice: An explanation based on the potential energy landscape Journal Article
In: The Journal of Chemical Physics, vol. 147, no. 4, pp. 044501, 2017.
Abstract | BibTeX | Tags: Glass Formation, Polyamorphism, Water | Links:
@article{gsp17,
title = {Influence of sample preparation on the transformation of low-density to high-density amorphous ice: An explanation based on the potential energy landscape},
author = {Nicolas Giovambattista and Francis W. Starr and Peter H. Poole},
url = {http://fstarr.web.wesleyan.edu/publications/gsp17.pdf},
doi = {10.1063/1.499356},
year = {2017},
date = {2017-07-25},
journal = {The Journal of Chemical Physics},
volume = {147},
number = {4},
pages = {044501},
abstract = {Experiments and computer simulations of the transformations of amorphous ices display different behaviors depending on sample preparation methods and on the rates of change of temperature and pressure to which samples are subjected. In addition to these factors, simulation results also depend strongly on the chosen water model. Using computer simulations of the ST2 water model, we study how the sharpness of the compression-induced transition from low-density amorphous ice (LDA) to high-density amorphous ice (HDA) is influenced by the preparation of LDA. By studying LDA samples prepared using widely different procedures, we find that the sharpness of the LDA-to-HDA transformation is correlated with the depth of the initial LDA sample in the potential energy landscape (PEL), as characterized by the inherent structure energy. Our results show that the complex phenomenology of the amorphous ices reported in experiments and computer simulations can be understood and predicted in a unified way from knowledge of the PEL of the system.},
keywords = {Glass Formation, Polyamorphism, Water},
pubstate = {published},
tppubtype = {article}
}
Experiments and computer simulations of the transformations of amorphous ices display different behaviors depending on sample preparation methods and on the rates of change of temperature and pressure to which samples are subjected. In addition to these factors, simulation results also depend strongly on the chosen water model. Using computer simulations of the ST2 water model, we study how the sharpness of the compression-induced transition from low-density amorphous ice (LDA) to high-density amorphous ice (HDA) is influenced by the preparation of LDA. By studying LDA samples prepared using widely different procedures, we find that the sharpness of the LDA-to-HDA transformation is correlated with the depth of the initial LDA sample in the potential energy landscape (PEL), as characterized by the inherent structure energy. Our results show that the complex phenomenology of the amorphous ices reported in experiments and computer simulations can be understood and predicted in a unified way from knowledge of the PEL of the system.
2016
Giovambattista, Nicolas; Sciortino, Francesco; Starr, Francis W.; Poole, Peter H.
Potential energy landscape of the apparent first-order phase transition between low-density and high-density amorphous ice Journal Article
In: The Journal of Chemical Physics, vol. 145, no. 22, pp. 224501, 2016.
BibTeX | Tags: Glass Formation, Polyamorphism, Water | Links:
@article{gssp16,
title = {Potential energy landscape of the apparent first-order phase transition between low-density and high-density amorphous ice},
author = {Giovambattista, Nicolas and Sciortino, Francesco and Starr, Francis W. and Poole, Peter H.},
url = {http://fstarr.web.wesleyan.edu/publications/gssp16.pdf},
doi = {http://dx.doi.org/10.1063/1.4968047},
year = {2016},
date = {2016-01-01},
journal = {The Journal of Chemical Physics},
volume = {145},
number = {22},
pages = {224501},
keywords = {Glass Formation, Polyamorphism, Water},
pubstate = {published},
tppubtype = {article}
}
2014
Starr, Francis W.
PHYSICS OF WATER Crystal-clear transition Journal Article
In: NATURE PHYSICS, vol. 10, no. 9, pp. 628-629, 2014, ISSN: 1745-2473.
BibTeX | Tags: Polyamorphism, Water | Links:
@article{snv14,
title = {PHYSICS OF WATER Crystal-clear transition},
author = {Starr, Francis W.},
url = {http://fstarr.web.wesleyan.edu/publications/snv14.pdf},
doi = {10.1038/nphys3059},
issn = {1745-2473},
year = {2014},
date = {2014-09-01},
journal = {NATURE PHYSICS},
volume = {10},
number = {9},
pages = {628-629},
keywords = {Polyamorphism, Water},
pubstate = {published},
tppubtype = {article}
}
Chiu, Janet; Starr, Francis W.; Giovambattista, Nicolas
Heating-induced glass-glass and glass-liquid transformations in computer simulations of water Journal Article
In: JOURNAL OF CHEMICAL PHYSICS, vol. 140, no. 11, pp. 114504, 2014, ISSN: 0021-9606.
Abstract | BibTeX | Tags: Glass Formation, Polyamorphism, Water | Links:
@article{csg14,
title = {Heating-induced glass-glass and glass-liquid transformations in computer simulations of water},
author = {Chiu, Janet and Starr, Francis W. and Giovambattista, Nicolas},
url = {http://fstarr.web.wesleyan.edu/publications/csg14.pdf},
doi = {10.1063/1.4868028},
issn = {0021-9606},
year = {2014},
date = {2014-03-01},
journal = {JOURNAL OF CHEMICAL PHYSICS},
volume = {140},
number = {11},
pages = {114504},
abstract = {Water exists in at least two families of glassy states, broadly categorized as the low-density (LDA) and high-density amorphous ice (HDA). Remarkably, LDA and HDA can be reversibly interconverted via appropriate thermodynamic paths, such as isothermal compression and isobaric heating, exhibiting first-order-like phase transitions. We perform out-of-equilibrium molecular dynamics simulations of glassy water using the ST2 model to study the evolution of LDA and HDA upon isobaric heating. Depending on pressure, glass-to-glass, glass-to-crystal, glass-to-vapor, as well as glass-to-liquid transformations are found. Specifically, heating LDA results in the following transformations, with increasing heating pressures: (i) LDA-to-vapor (sublimation), (ii) LDA-to-liquid (glass transition), (iii) LDA-to-HDA-to-liquid, (iv) LDA-to-HDA-to-liquid-to-crystal, and (v) LDA-to- HDA-to-crystal. Similarly, heating HDA results in the following transformations, with decreasing heating pressures: (a) HDA-to-crystal, (b) HDA-to-liquid-to-crystal, (c) HDA-to-liquid (glass transition), (d) HDA-to-LDA-to-liquid, and (e) HDA-to-LDA-to-vapor. A more complex sequence may be possible using lower heating rates. For each of these transformations, we determine the corresponding transformation temperature as function of pressure, and provide a P-T ``phase diagram'' for glassy water based on isobaric heating. Our results for isobaric heating dovetail with the LDA-HDA transformations reported for ST2 glassy water based on isothermal compression/decompression processes [ Chiu et al., J. Chem. Phys. 139, 184504 (2013)]. The resulting phase diagram is consistent with the liquid-liquid phase transition hypothesis. At the same time, the glass phase diagram is sensitive to sample preparation, such as heating or compression rates. Interestingly, at least for the rates explored, our results suggest that the LDA-to-liquid (HDA-to-liquid) and LDA-to-HDA (HDA-to-LDA) transformation lines on heating are related, both being associated with the limit of kinetic stability of LDA (HDA). (C) 2014 AIP Publishing LLC.},
keywords = {Glass Formation, Polyamorphism, Water},
pubstate = {published},
tppubtype = {article}
}
Water exists in at least two families of glassy states, broadly categorized as the low-density (LDA) and high-density amorphous ice (HDA). Remarkably, LDA and HDA can be reversibly interconverted via appropriate thermodynamic paths, such as isothermal compression and isobaric heating, exhibiting first-order-like phase transitions. We perform out-of-equilibrium molecular dynamics simulations of glassy water using the ST2 model to study the evolution of LDA and HDA upon isobaric heating. Depending on pressure, glass-to-glass, glass-to-crystal, glass-to-vapor, as well as glass-to-liquid transformations are found. Specifically, heating LDA results in the following transformations, with increasing heating pressures: (i) LDA-to-vapor (sublimation), (ii) LDA-to-liquid (glass transition), (iii) LDA-to-HDA-to-liquid, (iv) LDA-to-HDA-to-liquid-to-crystal, and (v) LDA-to- HDA-to-crystal. Similarly, heating HDA results in the following transformations, with decreasing heating pressures: (a) HDA-to-crystal, (b) HDA-to-liquid-to-crystal, (c) HDA-to-liquid (glass transition), (d) HDA-to-LDA-to-liquid, and (e) HDA-to-LDA-to-vapor. A more complex sequence may be possible using lower heating rates. For each of these transformations, we determine the corresponding transformation temperature as function of pressure, and provide a P-T ``phase diagram'' for glassy water based on isobaric heating. Our results for isobaric heating dovetail with the LDA-HDA transformations reported for ST2 glassy water based on isothermal compression/decompression processes [ Chiu et al., J. Chem. Phys. 139, 184504 (2013)]. The resulting phase diagram is consistent with the liquid-liquid phase transition hypothesis. At the same time, the glass phase diagram is sensitive to sample preparation, such as heating or compression rates. Interestingly, at least for the rates explored, our results suggest that the LDA-to-liquid (HDA-to-liquid) and LDA-to-HDA (HDA-to-LDA) transformation lines on heating are related, both being associated with the limit of kinetic stability of LDA (HDA). (C) 2014 AIP Publishing LLC.
Starr, Francis W.; Sciortino, Francesco
``Crystal-clear'' liquid-liquid transition in a tetrahedral fluid Journal Article
In: SOFT MATTER, vol. 10, no. 47, pp. 9413-9422, 2014, ISSN: 1744-683X.
Abstract | BibTeX | Tags: DNA, Polyamorphism | Links:
@article{ss14,
title = {``Crystal-clear'' liquid-liquid transition in a tetrahedral fluid},
author = {Starr, Francis W. and Sciortino, Francesco},
url = {http://fstarr.web.wesleyan.edu/publications/ss14.pdf},
doi = {10.1039/c4sm01835d},
issn = {1744-683X},
year = {2014},
date = {2014-01-01},
journal = {SOFT MATTER},
volume = {10},
number = {47},
pages = {9413-9422},
abstract = {For a model known to exhibit liquid-liquid transitions, we examine how varying the bond orientational flexibility affects the stability of the liquid-liquid transition relative to that of the crystal phases. For very rigidly oriented bonds, the crystal is favored over all amorphous phase transitions. We find that increasing the bond flexibility decreases both the critical temperature T-c for liquid-liquid phase separation and the melting temperature T-m. The effect of increasing flexibility is much stronger for melting, so that the distance between T-c and T-m progressively reduces and inverts sign. Under these conditions, a ``naked'' liquid-liquid critical point bulges out in the liquid phase and becomes accessible, without the possibility of crystallization. These results confirm that a crystal-clear, liquid-liquid transition can occur as a genuine, thermodynamically stable phenomenon for tetrahedral coordinated particles with flexible bond orientation, but that such a transition is hidden by crystallization when bonds are highly directional.},
keywords = {DNA, Polyamorphism},
pubstate = {published},
tppubtype = {article}
}
For a model known to exhibit liquid-liquid transitions, we examine how varying the bond orientational flexibility affects the stability of the liquid-liquid transition relative to that of the crystal phases. For very rigidly oriented bonds, the crystal is favored over all amorphous phase transitions. We find that increasing the bond flexibility decreases both the critical temperature T-c for liquid-liquid phase separation and the melting temperature T-m. The effect of increasing flexibility is much stronger for melting, so that the distance between T-c and T-m progressively reduces and inverts sign. Under these conditions, a ``naked'' liquid-liquid critical point bulges out in the liquid phase and becomes accessible, without the possibility of crystallization. These results confirm that a crystal-clear, liquid-liquid transition can occur as a genuine, thermodynamically stable phenomenon for tetrahedral coordinated particles with flexible bond orientation, but that such a transition is hidden by crystallization when bonds are highly directional.
2013
Chiu, Janet; Starr, Francis W.; Giovambattista, Nicolas
Pressure-induced transformations in computer simulations of glassy water Journal Article
In: JOURNAL OF CHEMICAL PHYSICS, vol. 139, no. 18, pp. 184504, 2013, ISSN: 0021-9606.
Abstract | BibTeX | Tags: Glass Formation, Polyamorphism, Water | Links:
@article{csg13,
title = {Pressure-induced transformations in computer simulations of glassy water},
author = {Chiu, Janet and Starr, Francis W. and Giovambattista, Nicolas},
url = {http://fstarr.web.wesleyan.edu/publications/csg13.pdf},
doi = {10.1063/1.4829276},
issn = {0021-9606},
year = {2013},
date = {2013-11-01},
journal = {JOURNAL OF CHEMICAL PHYSICS},
volume = {139},
number = {18},
pages = {184504},
abstract = {Glassy water occurs in at least two broad categories: low-density amorphous (LDA) and high-density amorphous (HDA) solid water. We perform out-of-equilibrium molecular dynamics simulations to study the transformations of glassy water using the ST2 model. Specifically, we study the known (i) compression-induced LDA-to-HDA, (ii) decompression-induced HDA-to-LDA, and (iii) compression-induced hexagonal ice-to-HDA transformations. We study each transformation for a broad range of compression/decompression temperatures, enabling us to construct a ``P-T phase diagram'' for glassy water. The resulting phase diagram shows the same qualitative features reported from experiments. While many simulations have probed the liquid-state phase behavior, comparatively little work has examined the transitions of glassy water. We examine how the glass transformations relate to the (first-order) liquid-liquid phase transition previously reported for this model. Specifically, our results support the hypothesis that the liquid-liquid spinodal lines, between a low-density and high-density liquid, are extensions of the LDA-HDA transformation lines in the limit of slow compression. Extending decompression runs to negative pressures, we locate the sublimation lines for both LDA and hyperquenched glassy water (HGW), and find that HGW is relatively more stable to the vapor. Additionally, we observe spontaneous crystallization of HDA at high pressure to ice VII. Experiments have also seen crystallization of HDA, but to ice XII. Finally, we contrast the structure of LDA and HDA for the ST2 model with experiments. We find that while the radial distribution functions (RDFs) of LDA are similar to those observed in experiments, considerable differences exist between the HDA RDFs of ST2 water and experiment. The differences in HDA structure, as well as the formation of ice VII (a tetrahedral crystal), are a consequence of ST2 overemphasizing the tetrahedral character of water. (C) 2013 AIP Publishing LLC.},
keywords = {Glass Formation, Polyamorphism, Water},
pubstate = {published},
tppubtype = {article}
}
Glassy water occurs in at least two broad categories: low-density amorphous (LDA) and high-density amorphous (HDA) solid water. We perform out-of-equilibrium molecular dynamics simulations to study the transformations of glassy water using the ST2 model. Specifically, we study the known (i) compression-induced LDA-to-HDA, (ii) decompression-induced HDA-to-LDA, and (iii) compression-induced hexagonal ice-to-HDA transformations. We study each transformation for a broad range of compression/decompression temperatures, enabling us to construct a ``P-T phase diagram'' for glassy water. The resulting phase diagram shows the same qualitative features reported from experiments. While many simulations have probed the liquid-state phase behavior, comparatively little work has examined the transitions of glassy water. We examine how the glass transformations relate to the (first-order) liquid-liquid phase transition previously reported for this model. Specifically, our results support the hypothesis that the liquid-liquid spinodal lines, between a low-density and high-density liquid, are extensions of the LDA-HDA transformation lines in the limit of slow compression. Extending decompression runs to negative pressures, we locate the sublimation lines for both LDA and hyperquenched glassy water (HGW), and find that HGW is relatively more stable to the vapor. Additionally, we observe spontaneous crystallization of HDA at high pressure to ice VII. Experiments have also seen crystallization of HDA, but to ice XII. Finally, we contrast the structure of LDA and HDA for the ST2 model with experiments. We find that while the radial distribution functions (RDFs) of LDA are similar to those observed in experiments, considerable differences exist between the HDA RDFs of ST2 water and experiment. The differences in HDA structure, as well as the formation of ice VII (a tetrahedral crystal), are a consequence of ST2 overemphasizing the tetrahedral character of water. (C) 2013 AIP Publishing LLC.
2012
Giovambattista, Nicolas; Loerting, Thomas; Lukanov, Boris R.; Starr, Francis W.
Interplay of the Glass Transition and the Liquid-Liquid Phase Transition in Water Journal Article
In: SCIENTIFIC REPORTS, vol. 2, pp. 390, 2012, ISSN: 2045-2322.
Abstract | BibTeX | Tags: Glass Formation, Polyamorphism, Water | Links:
@article{glls12,
title = {Interplay of the Glass Transition and the Liquid-Liquid Phase Transition in Water},
author = {Giovambattista, Nicolas and Loerting, Thomas and Lukanov, Boris R. and Starr, Francis W.},
url = {http://fstarr.web.wesleyan.edu/publications/glls12.pdf},
doi = {10.1038/srep00390},
issn = {2045-2322},
year = {2012},
date = {2012-05-01},
journal = {SCIENTIFIC REPORTS},
volume = {2},
pages = {390},
abstract = {Water has multiple glassy states, often called amorphous ices. Low-density (LDA) and high-density (HDA) amorphous ice are separated by a dramatic, first-order like phase transition. It has been argued that the LDA-HDA transformation connects to a first-order liquid-liquid phase transition (LLPT) above the glass transition temperature T-g. Direct experimental evidence of the LLPT is challenging to obtain, since the LLPT occurs at conditions where water rapidly crystallizes. In this work, we explore the implications of a LLPT on the pressure dependence of T-g(P) for LDA and HDA by performing computer simulations of two water models - one with a LLPT, and one without. In the absence of a LLPT, T-g(P) for all glasses nearly coincide. When there is a LLPT, different glasses exhibit dramatically different T-g(P) which are directly linked with the LLPT. Available experimental data for T-g(P) are only consistent with the scenario including a LLPT.},
keywords = {Glass Formation, Polyamorphism, Water},
pubstate = {published},
tppubtype = {article}
}
Water has multiple glassy states, often called amorphous ices. Low-density (LDA) and high-density (HDA) amorphous ice are separated by a dramatic, first-order like phase transition. It has been argued that the LDA-HDA transformation connects to a first-order liquid-liquid phase transition (LLPT) above the glass transition temperature T-g. Direct experimental evidence of the LLPT is challenging to obtain, since the LLPT occurs at conditions where water rapidly crystallizes. In this work, we explore the implications of a LLPT on the pressure dependence of T-g(P) for LDA and HDA by performing computer simulations of two water models - one with a LLPT, and one without. In the absence of a LLPT, T-g(P) for all glasses nearly coincide. When there is a LLPT, different glasses exhibit dramatically different T-g(P) which are directly linked with the LLPT. Available experimental data for T-g(P) are only consistent with the scenario including a LLPT.
2011
Poole, Peter H.; Becker, Stephen R.; Sciortino, Francesco; Starr, Francis W.
Dynamical Behavior Near a Liquid-Liquid Phase Transition in Simulations of Supercooled Water Journal Article
In: JOURNAL OF PHYSICAL CHEMISTRY B, vol. 115, no. 48, pp. 14176-14183, 2011, ISSN: 1520-6106.
Abstract | BibTeX | Tags: Polyamorphism, Water | Links:
@article{pbss11,
title = {Dynamical Behavior Near a Liquid-Liquid Phase Transition in Simulations of Supercooled Water},
author = {Poole, Peter H. and Becker, Stephen R. and Sciortino, Francesco and Starr, Francis W.},
url = {http://fstarr.web.wesleyan.edu/publications/pbss11.pdf},
doi = {10.1021/jp204889m},
issn = {1520-6106},
year = {2011},
date = {2011-12-01},
journal = {JOURNAL OF PHYSICAL CHEMISTRY B},
volume = {115},
number = {48},
pages = {14176-14183},
abstract = {We examine the behavior of the diffusion coefficient of the ST2 model of water over a broad region of the phase diagram via molecular dynamics simulations. The ST2 model has an accessible liquid-liquid transition between low-density and high-density phases, making the model an ideal candidate to explore the impacts of the liquid-liquid transition on dynamics. We locate characteristic dynamical loci in the phase diagram and compare them with the previously investigated thermodynamic loci. The low-density liquid phase shows a crossover from non-Arrhenius to Arrhenius behavior, signaling the onset of a crossover from fragile-to-strong behavior. We explain this crossover in terms of the asymptotic approach of the low-density liquid to a random tetrahedral network and show that the temperature dependence of the diffusion coefficient over a wide temperature range can be simply related to the concentration of defects in the network. Our findings thus confirm that the low-density phase of ST2 water is a well-defined metastable liquid.},
keywords = {Polyamorphism, Water},
pubstate = {published},
tppubtype = {article}
}
We examine the behavior of the diffusion coefficient of the ST2 model of water over a broad region of the phase diagram via molecular dynamics simulations. The ST2 model has an accessible liquid-liquid transition between low-density and high-density phases, making the model an ideal candidate to explore the impacts of the liquid-liquid transition on dynamics. We locate characteristic dynamical loci in the phase diagram and compare them with the previously investigated thermodynamic loci. The low-density liquid phase shows a crossover from non-Arrhenius to Arrhenius behavior, signaling the onset of a crossover from fragile-to-strong behavior. We explain this crossover in terms of the asymptotic approach of the low-density liquid to a random tetrahedral network and show that the temperature dependence of the diffusion coefficient over a wide temperature range can be simply related to the concentration of defects in the network. Our findings thus confirm that the low-density phase of ST2 water is a well-defined metastable liquid.
2010
Dai, Wei; Hsu, Chia Wei; Sciortino, Francesco; Starr, Francis W.
Valency Dependence of Polymorphism and Polyamorphism in DNA-Functionalized Nanoparticles Journal Article
In: LANGMUIR, vol. 26, no. 5, pp. 3601-3608, 2010, ISSN: 0743-7463.
Abstract | BibTeX | Tags: Biophysics, DNA, Nanotechnology, Polyamorphism | Links:
@article{dhss10,
title = {Valency Dependence of Polymorphism and Polyamorphism in DNA-Functionalized Nanoparticles},
author = {Dai, Wei and Hsu, Chia Wei and Sciortino, Francesco and Starr, Francis W.},
url = {http://fstarr.web.wesleyan.edu/publications/dhss.pdf},
doi = {10.1021/la903031p},
issn = {0743-7463},
year = {2010},
date = {2010-03-01},
journal = {LANGMUIR},
volume = {26},
number = {5},
pages = {3601-3608},
abstract = {Nanoparticles (NP) functionalized with single-stranded DNA (ssDNA) offer a route to custom-designed, self-assembled nanomaterials with potentially unusual properties, The bonding, selectivity of DNA guarantees one-to-one binding to form double-stranded DNA (dsDNA), and an appropriate base sequence results in head-to-tail binding linking NP into networks. We explore the phase behavior and structure of a model for NP functionalized with between 3 and 6 short ssDNA through simulations of a coarse-grained molecular model, allowing us to examine both the role of the number of attached strands (valency) and their relative orientations. The NP assemble into networks where the number of NP links is controlled by the number of attached strands, The large length scale of the DNA links relative to the core NP size opens the possibility for the formation of interpenetrating networks that give rise 10 multiple thermodynamically distinct states. We find that the 3-functionalized NP have only a single phase transition between a dilute solution of NPs and an assembled network state. 4-Functionalized NP (with tetrahedral symmetry) exhibit four amorphous phases, or polyamorphism, each higher density phase consisting of an additional interpenetrating network. The two investigated geometries of 5-functionalized NP both exhibit two phase transitions and three amorphouos phases. Like the 4-functionalized NP, the highest density phase consists of interpenetrating networks, demonstrating that regular symmetry is not a prerequisite for interpenetration to produce thermodynamically distinct phases. The width of theh coexistence regions for all phase transitions increase with increasing functionality. Finally, for 6-functionalized NP with octahedral symmetry. the possibility of observing disordered phases with significantly bonded particles is preempted by the formation of ordered crystal phases, Interestingly, the extreme softness of the potential combined with the directional interaction allows for the formation of (at least) six distinct crystalline structures (ie., polymorphism) consisting of up to six interpenetrating simple cubic lattices.},
keywords = {Biophysics, DNA, Nanotechnology, Polyamorphism},
pubstate = {published},
tppubtype = {article}
}
Nanoparticles (NP) functionalized with single-stranded DNA (ssDNA) offer a route to custom-designed, self-assembled nanomaterials with potentially unusual properties, The bonding, selectivity of DNA guarantees one-to-one binding to form double-stranded DNA (dsDNA), and an appropriate base sequence results in head-to-tail binding linking NP into networks. We explore the phase behavior and structure of a model for NP functionalized with between 3 and 6 short ssDNA through simulations of a coarse-grained molecular model, allowing us to examine both the role of the number of attached strands (valency) and their relative orientations. The NP assemble into networks where the number of NP links is controlled by the number of attached strands, The large length scale of the DNA links relative to the core NP size opens the possibility for the formation of interpenetrating networks that give rise 10 multiple thermodynamically distinct states. We find that the 3-functionalized NP have only a single phase transition between a dilute solution of NPs and an assembled network state. 4-Functionalized NP (with tetrahedral symmetry) exhibit four amorphous phases, or polyamorphism, each higher density phase consisting of an additional interpenetrating network. The two investigated geometries of 5-functionalized NP both exhibit two phase transitions and three amorphouos phases. Like the 4-functionalized NP, the highest density phase consists of interpenetrating networks, demonstrating that regular symmetry is not a prerequisite for interpenetration to produce thermodynamically distinct phases. The width of theh coexistence regions for all phase transitions increase with increasing functionality. Finally, for 6-functionalized NP with octahedral symmetry. the possibility of observing disordered phases with significantly bonded particles is preempted by the formation of ordered crystal phases, Interestingly, the extreme softness of the potential combined with the directional interaction allows for the formation of (at least) six distinct crystalline structures (ie., polymorphism) consisting of up to six interpenetrating simple cubic lattices.
2009
Xu, Limei; Mallamace, Francesco; Yan, Zhenyu; Starr, Francis W.; Buldyrev, Sergey V.; Stanley, H. Eugene
Appearance of a fractional Stokes-Einstein relation in water and a structural interpretation of its onset Journal Article
In: NATURE PHYSICS, vol. 5, no. 8, pp. 565-569, 2009, ISSN: 1745-2473.
Abstract | BibTeX | Tags: Glass Formation, Polyamorphism, Water | Links:
@article{xmysbs,
title = {Appearance of a fractional Stokes-Einstein relation in water and a structural interpretation of its onset},
author = {Xu, Limei and Mallamace, Francesco and Yan, Zhenyu and Starr, Francis W. and Buldyrev, Sergey V. and Stanley, H. Eugene},
url = {http://fstarr.web.wesleyan.edu/publications/xmysbs.pdf},
doi = {10.1038/NPHYS1328},
issn = {1745-2473},
year = {2009},
date = {2009-08-01},
journal = {NATURE PHYSICS},
volume = {5},
number = {8},
pages = {565-569},
abstract = {The Stokes-Einstein relation has long been regarded as one of the hallmarks of transport in liquids. It predicts that the self-diffusion constant D is proportional to (tau/T)(-1), where tau is the structural relaxation time and T is the temperature. Here, we present experimental data on water confirming that, below a crossover temperature T-x approximate to 290 K, the Stokes-Einstein relation is replaced by a `fractional' Stokes-Einstein relation D similar to (tau/T)(-zeta) with zeta approximate to 3/5 (refs 1-6). We interpret the microscopic origin of this crossover by analysing the OH-stretch region of the Fourier transform infrared spectrum over a temperature range from 350 down to 200 K. Simultaneous with the onset of fractional Stokes-Einstein behaviour, we find that water begins to develop a local structure similar to that of low-density amorphous solid H2O. These data lead to an interpretation that the fractional Stokes-Einstein relation in water arises from a specific change in the local water structure. Computer simulations of two molecular models further support this interpretation.},
keywords = {Glass Formation, Polyamorphism, Water},
pubstate = {published},
tppubtype = {article}
}
The Stokes-Einstein relation has long been regarded as one of the hallmarks of transport in liquids. It predicts that the self-diffusion constant D is proportional to (tau/T)(-1), where tau is the structural relaxation time and T is the temperature. Here, we present experimental data on water confirming that, below a crossover temperature T-x approximate to 290 K, the Stokes-Einstein relation is replaced by a `fractional' Stokes-Einstein relation D similar to (tau/T)(-zeta) with zeta approximate to 3/5 (refs 1-6). We interpret the microscopic origin of this crossover by analysing the OH-stretch region of the Fourier transform infrared spectrum over a temperature range from 350 down to 200 K. Simultaneous with the onset of fractional Stokes-Einstein behaviour, we find that water begins to develop a local structure similar to that of low-density amorphous solid H2O. These data lead to an interpretation that the fractional Stokes-Einstein relation in water arises from a specific change in the local water structure. Computer simulations of two molecular models further support this interpretation.
Hsu, Chia Wei; Starr, Francis W.
Interpenetration as a mechanism for liquid-liquid phase transitions Journal Article
In: PHYSICAL REVIEW E, vol. 79, no. 4, 1, pp. 041502, 2009, ISSN: 1539-3755.
Abstract | BibTeX | Tags: Polyamorphism | Links:
@article{hs09,
title = {Interpenetration as a mechanism for liquid-liquid phase transitions},
author = {Hsu, Chia Wei and Starr, Francis W.},
url = {http://fstarr.web.wesleyan.edu/publications/hs.pdf},
doi = {10.1103/PhysRevE.79.041502},
issn = {1539-3755},
year = {2009},
date = {2009-04-01},
journal = {PHYSICAL REVIEW E},
volume = {79},
number = {4, 1},
pages = {041502},
abstract = {We study simple lattice systems to demonstrate the influence of interpenetrating bond networks on phase behavior. We promote interpenetration by using a Hamiltonian with a weakly repulsive interaction with nearest neighbors and an attractive interaction with second-nearest neighbors. In this way, bond networks will form between second-nearest neighbors, allowing for two (locally) distinct networks to form. We obtain the phase behavior from analytic solution in the mean-field approximation and exact solution on the Bethe lattice. We compare these results with exact numerical results for the phase behavior from grand canonical Monte Carlo simulations on square, cubic, and tetrahedral lattices. All results show that these simple systems exhibit rich phase diagrams with two fluid-fluid critical points and three thermodynamically distinct phases. We also consider including third-nearest-neighbor interactions, which give rise to a phase diagram with four critical points and five thermodynamically distinct phases. Thus the interpenetration mechanism provides a simple route to generate multiple liquid phases in single-component systems, such as hypothesized in water and observed in several model and experimental systems. Additionally, interpenetration of many such networks appears plausible in a recently considered material made from nanoparticles functionalized by single-strands of DNA.},
keywords = {Polyamorphism},
pubstate = {published},
tppubtype = {article}
}
We study simple lattice systems to demonstrate the influence of interpenetrating bond networks on phase behavior. We promote interpenetration by using a Hamiltonian with a weakly repulsive interaction with nearest neighbors and an attractive interaction with second-nearest neighbors. In this way, bond networks will form between second-nearest neighbors, allowing for two (locally) distinct networks to form. We obtain the phase behavior from analytic solution in the mean-field approximation and exact solution on the Bethe lattice. We compare these results with exact numerical results for the phase behavior from grand canonical Monte Carlo simulations on square, cubic, and tetrahedral lattices. All results show that these simple systems exhibit rich phase diagrams with two fluid-fluid critical points and three thermodynamically distinct phases. We also consider including third-nearest-neighbor interactions, which give rise to a phase diagram with four critical points and five thermodynamically distinct phases. Thus the interpenetration mechanism provides a simple route to generate multiple liquid phases in single-component systems, such as hypothesized in water and observed in several model and experimental systems. Additionally, interpenetration of many such networks appears plausible in a recently considered material made from nanoparticles functionalized by single-strands of DNA.
2008
Hsu, Chia Wei; Largo, Julio; Sciortino, Francesco; Starr, Francis W.
Hierarchies of networked phases induced by multiple liquid-liquid critical points Journal Article
In: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, vol. 105, no. 37, pp. 13711-13715, 2008, ISSN: 0027-8424.
Abstract | BibTeX | Tags: Biophysics, DNA, Polyamorphism, Self Assembly, Water | Links:
@article{hlss08,
title = {Hierarchies of networked phases induced by multiple liquid-liquid critical points},
author = {Hsu, Chia Wei and Largo, Julio and Sciortino, Francesco and Starr, Francis W.},
url = {http://fstarr.web.wesleyan.edu/publications/hlss.pdf},
doi = {10.1073/pnas.0804854105},
issn = {0027-8424},
year = {2008},
date = {2008-09-01},
journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA},
volume = {105},
number = {37},
pages = {13711-13715},
abstract = {Nanoparticles and colloids functionalized by four single strands of DNA can be thought of as designed analogs to tetrahedral network-forming atoms and molecules, with a difference that the attached DNA strands allow for control of the length scale of bonding relative to the core size. We explore the behavior of an experimentally realized model for nanoparticles functionalized by four single strands of DNA (a tetramer), and show that this single-component model exhibits a rich phase diagram with at least three critical points and four thermodynamically distinct amorphous phases. We demonstrate that the additional critical points are part of the Ising universality class, like the ordinary liquid-gas critical point. The dense phases consist of a hierarchy of interpenetrating networks, reminiscent of a woven cloth. Thus, bonding specificity of DNA provides an effective route to generate new nano-networked materials with polyamorphic behavior. The concept of network interpenetration helps to explain the generation of multiple liquid phases in sing le-component systems, suggested to occur in some atomic and molecular network-forming fluids, including water and silica.},
keywords = {Biophysics, DNA, Polyamorphism, Self Assembly, Water},
pubstate = {published},
tppubtype = {article}
}
Nanoparticles and colloids functionalized by four single strands of DNA can be thought of as designed analogs to tetrahedral network-forming atoms and molecules, with a difference that the attached DNA strands allow for control of the length scale of bonding relative to the core size. We explore the behavior of an experimentally realized model for nanoparticles functionalized by four single strands of DNA (a tetramer), and show that this single-component model exhibits a rich phase diagram with at least three critical points and four thermodynamically distinct amorphous phases. We demonstrate that the additional critical points are part of the Ising universality class, like the ordinary liquid-gas critical point. The dense phases consist of a hierarchy of interpenetrating networks, reminiscent of a woven cloth. Thus, bonding specificity of DNA provides an effective route to generate new nano-networked materials with polyamorphic behavior. The concept of network interpenetration helps to explain the generation of multiple liquid phases in sing le-component systems, suggested to occur in some atomic and molecular network-forming fluids, including water and silica.
2007
Kumar, Pradeep; Buldyrev, Sergey V.; Becker, Stephen R.; Poole, Peter H.; Starr, Francis W.; Stanley, H. Eugene
Relation between the Widom line and the breakdown of the Stokes-Einstein relation in supercooled water Journal Article
In: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, vol. 104, no. 23, pp. 9575-9579, 2007, ISSN: 0027-8424.
Abstract | BibTeX | Tags: Glass Formation, Polyamorphism, Water | Links:
@article{kbbpss,
title = {Relation between the Widom line and the breakdown of the Stokes-Einstein relation in supercooled water},
author = {Kumar, Pradeep and Buldyrev, Sergey V. and Becker, Stephen R. and Poole, Peter H. and Starr, Francis W. and Stanley, H. Eugene},
url = {http://fstarr.web.wesleyan.edu/publications/kbbpss.pdf},
doi = {10.1073/pnas.0702608104},
issn = {0027-8424},
year = {2007},
date = {2007-06-01},
journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA},
volume = {104},
number = {23},
pages = {9575-9579},
abstract = {Supercooled water exhibits a breakdown of the Stokes-Einstein relation between the diffusion constant D and the alpha relaxation time $tau(alpha)$. For water simulated with two different potentials, TIP5P and ST2, we find that the temperature of the decoupling of diffusion and alpha relaxation correlates with the temperature of the maximum in specific heat that corresponds to crossing the Widom line T(W)(P). Specifically, we find that our results for D tau(alpha)/T collapse onto a single ``master curve'' if temperature is replaced by T - T(W)(P). We further find that the size of the mobile molecule clusters (dynamical heterogeneities) increases sharply near T(W)w(P). Moreover, our calculations of mobile particle cluster size < n(t*)>(w) for different pressures, where t* is the time for which the mobile particle cluster size is largest, also collapse onto a single master curve if T is, replaced by T - T(W)(P). The crossover to a more locally structured low density liquid (LDL) as T -> T(W)(P) appears to be well correlated both with the breakdown of the Stokes-Einstein relation and with the growth of dynamic heterogeneities. Our results are consistent with the possibility that the breakdown of the SE relation in supercooled water at low pressures is associated with the hypothesized liquid-liquid phase transition.},
keywords = {Glass Formation, Polyamorphism, Water},
pubstate = {published},
tppubtype = {article}
}
Supercooled water exhibits a breakdown of the Stokes-Einstein relation between the diffusion constant D and the alpha relaxation time $tau(alpha)$. For water simulated with two different potentials, TIP5P and ST2, we find that the temperature of the decoupling of diffusion and alpha relaxation correlates with the temperature of the maximum in specific heat that corresponds to crossing the Widom line T(W)(P). Specifically, we find that our results for D tau(alpha)/T collapse onto a single ``master curve'' if temperature is replaced by T - T(W)(P). We further find that the size of the mobile molecule clusters (dynamical heterogeneities) increases sharply near T(W)w(P). Moreover, our calculations of mobile particle cluster size < n(t*)>(w) for different pressures, where t* is the time for which the mobile particle cluster size is largest, also collapse onto a single master curve if T is, replaced by T - T(W)(P). The crossover to a more locally structured low density liquid (LDL) as T -> T(W)(P) appears to be well correlated both with the breakdown of the Stokes-Einstein relation and with the growth of dynamic heterogeneities. Our results are consistent with the possibility that the breakdown of the SE relation in supercooled water at low pressures is associated with the hypothesized liquid-liquid phase transition.
2003
Starr, Francis W.; Angell, C. Austen; Stanley, H. Eugene
Prediction of entropy and dynamic properties of water below the homogeneous nucleation temperature Journal Article
In: PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS, vol. 323, pp. 51-66, 2003, ISSN: 0378-4371.
Abstract | BibTeX | Tags: Glass Formation, Polyamorphism, Water | Links:
@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}
}
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.