Crystal growth dynamics in supercooled liquids probed by molecular dynamics

• Grant number: 22/05837-5
• Support Opportunities: Scholarships in Brazil - Post-Doctorate
• Effective date (Start): November 01, 2022
• Effective date (End): October 31, 2024
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Edgar Dutra Zanotto
• Grantee: Azat Tipeev
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated research grant: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass, AP.CEPID

Abstract

The present project is focused on the fundamental problem of crystal nuclei growth in supercooled liquids. Despite advances in laboratory experiments, it is still extremely difficult to experimentally determine certain key properties of growing tiny crystals as well as of highly metastable viscous liquids. New possibilities of learning about crystal growth at a microscopic level are available by powerful computer simulations, which allow us to obtain reliable information on the properties of the nanosized crystalline nuclei and to test growth theories. In this work, we plan to investigate the crystal growth mechanism and dynamics in pure germanium and in a binary AlCu alloy by utilizing high-performance parallel computer simulations, involving an AlCu potential developed via deep machine learning and a neural network algorithm. Various computational techniques will be used, e.g., the seeding method, mean lifetime method, the mean first passage time method, crystal structure identification, etc., which will allow us to directly obtain valuable microscopic information: the atomic attachment rate to the critical crystal nucleus, the critical nucleus size, the thermodynamic driving force, the heights of kinetic and thermodynamic barrier, the crystal growth velocity, and the viscosity and diffusion coefficients in a wide supercooling range, down to 30 % below the melting point. The simulation results will be compared with available literature experimental data (whenever possible), and then, be used to test the abilities of the Wilson-Frenkel, Broughton-Gilmer-Jackson, Kelton-Greer, and classical nucleation theories in predicting the crystal growth kinetics in Ge and AlCu liquids. These theoretical and computational findings will likely help to understand in detail the crystal growth dynamics at the atomistic level and shed light on several fundamental questions related to supercooled liquids. (AU)