TY - JOUR
T1 - Thermodynamics and kinetics of crystallization in deeply supercooled Stillinger-Weber silicon
AU - Goswami, Yagyik
AU - Vasisht, Vishwas V.
AU - Frenkel, Daan
AU - Debenedetti, Pablo G.
AU - Sastry, Srikanth
N1 - Funding Information:
The authors gratefully acknowledge the Thematic Unit of Excellence on Computational Materials Science and the National Supercomputing Mission facility (Param Yukti) at the Jawaharlal Nehru Center for Advanced Scientific Research for computational resources. S.S. acknowledges support through the JC Bose Fellowship (Grant No. JBR/2020/000015) SERB, DST (India). P.G.D. gratefully acknowledges support from the National Science Foundation (Grant No. CHE-1856704). The authors acknowledge with gratitude C. A. Angell for fruitful discussions regarding the subject of the manuscript and his insightful suggestions and ideas. Sebastiano Bernini is acknowledged for discussions and help in the early stages of this work.
Publisher Copyright:
© 2021 Author(s).
PY - 2021/11/21
Y1 - 2021/11/21
N2 - We study the kinetics of crystallization in deeply supercooled liquid silicon employing computer simulations and the Stillinger-Weber three-body potential. The free energy barriers to crystallization are computed using umbrella sampling Monte Carlo simulations and from unconstrained molecular dynamics simulations using a mean first passage time formulation. We focus on state points that have been described in earlier work [S. Sastry and C. A. Angell, Nat. Mater. 2, 739 (2003)] as straddling a liquid-liquid phase transition (LLPT) between two metastable liquid states. It was argued subsequently [Ricci et al., Mol. Phys. 117, 3254 (2019)] that the apparent transition is due to the loss of metastability of the liquid state with respect to the crystalline state. The presence of a barrier to crystallization for these state points is therefore of importance to ascertain, which we investigate, with due attention to ambiguities that may arise from the choice of order parameters. We find a well-defined free energy barrier to crystallization and demonstrate that both umbrella sampling and mean first passage time methods yield results that agree quantitatively. Our results thus provide strong evidence against the possibility that the liquids at state points close to the reported LLPT exhibit slow, spontaneous crystallization, but they do not address the existence of a LLPT (or lack thereof). We also compute the free energy barriers to crystallization at other state points over a broad range of temperatures and pressures and discuss the effect of changes in the microscopic structure of the metastable liquid on the free energy barrier heights.
AB - We study the kinetics of crystallization in deeply supercooled liquid silicon employing computer simulations and the Stillinger-Weber three-body potential. The free energy barriers to crystallization are computed using umbrella sampling Monte Carlo simulations and from unconstrained molecular dynamics simulations using a mean first passage time formulation. We focus on state points that have been described in earlier work [S. Sastry and C. A. Angell, Nat. Mater. 2, 739 (2003)] as straddling a liquid-liquid phase transition (LLPT) between two metastable liquid states. It was argued subsequently [Ricci et al., Mol. Phys. 117, 3254 (2019)] that the apparent transition is due to the loss of metastability of the liquid state with respect to the crystalline state. The presence of a barrier to crystallization for these state points is therefore of importance to ascertain, which we investigate, with due attention to ambiguities that may arise from the choice of order parameters. We find a well-defined free energy barrier to crystallization and demonstrate that both umbrella sampling and mean first passage time methods yield results that agree quantitatively. Our results thus provide strong evidence against the possibility that the liquids at state points close to the reported LLPT exhibit slow, spontaneous crystallization, but they do not address the existence of a LLPT (or lack thereof). We also compute the free energy barriers to crystallization at other state points over a broad range of temperatures and pressures and discuss the effect of changes in the microscopic structure of the metastable liquid on the free energy barrier heights.
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U2 - 10.1063/5.0069475
DO - 10.1063/5.0069475
M3 - Article
C2 - 34800966
AN - SCOPUS:85120159794
SN - 0021-9606
VL - 155
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
IS - 19
M1 - 194502
ER -