Successful test of the classical nucleation theory by molecular dynamic simulations of BaS

Author(s)

Costa Prado, Sandra Cristina ^[1] ; Rino, Jose Pedro ^{[2, 3]} ; Zanotto, Edgar D. ^{[3, 4]}

Affiliation

^[1] Fac Tecnol Mococa, Ave Dr Americo Pereira Lima S-N, BR-13736260 Mococa, SP - Brazil

^[2] Univ Fed Sao Carlos, Dept Fis, Via Washington Luiz Km 235, BR-13565905 Sao Carlos, SP - Brazil

^[3] Univ Fed Sao Carlos, Ctr Res Technol & Educ Vitreous Mat, Sao Carlos, SP - Brazil

^[4] Univ Fed Sao Carlos, Dept Engn Mat, Via Washington Luiz Km 235, BR-13565905 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: COMPUTATIONAL MATERIALS SCIENCE; v. 161, p. 99-106, APR 15 2019.
• Web of Science Citations: 0

Abstract

We used a recently developed two-body interatomic potential for barium sulfide (BaS), and performed molecular dynamics (MD) simulations with 36,000 particles to determine the kinetics of spontaneous, homogeneous nucleation and growth of BaS crystals in the supercooled liquid. Isothermal-isobaric MD simulations were accomplished at three temperatures. The calculated pair correlation function, along with several snapshots, allowed us to quantify the nucleation times, their crystal growth rates, and the time evolution of overall crystallization. Nucleation was spontaneously achieved in the supercooled liquid state; therefore, we computed the average birth times of the critical nuclei (also known as average onset time of the first nucleus) from 15 samples at each temperature, from which we computed the steady-state nucleation rates, MD J(ss)(T). Then, we independently obtained by MD the diffusion coefficients, D(T), the melting point, T-m, and the enthalpy of melting, Delta H-m. Thus, the MD J(ss) could be compared with the predictions of the Classical Nucleation Theory (CNT) for homogeneous nucleation using only one fitting parameter, the nucleus/liquid interfacial free energy, sigma. The calculated critical nucleus is made of only 2 to 3-unit cells, which is consistent with the critical size observed in the simulations, approximately 10-15 atoms. Using a constant (fitted value of) sigma, and the D(T) and thermo-dynamic parameters from the simulations, we found that the MD pre-exponential factor has the same order of magnitude as the theoretical value predicted by the CNT. To the best of our knowledge, this agreement of the predictions of CNT and MD simulations has seldom been reported. Therefore, our results corroborate the validity of the CNT for simple supercooled liquids. (AU)

• FAPESP's process: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass
• Grantee: Edgar Dutra Zanotto
• Support type: Research Grants - Research, Innovation and Dissemination Centers - RIDC