An atomistic model of MgSiO₃ perovskite and post-perovskite phases

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• 作者：C. Pinilla^a ; ^b ; ^{c.pinilla@ucl.ac.uk" class="auth_mail" title="E-mail the corresponding author} ; M. Acuñ ; a-Rojas^a ; N. Seriani^c ; S. Scandolo^c ; ^d
• 关键词：MgSiO3 phases ; Force fields ; Molecular dynamics ; Materials at extreme conditions
• 刊名：Computational Materials Science
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：126
• 期：Complete
• 页码：351-359
• 全文大小：705 K

文摘

A classical force field for MgSiO₃ polymorphs is presented and tested for the perovskite, post-perovskite and enstatite phases. In this force field each ion has a fixed partial charge and a fixed polarizability and the potential energy is minimised with respect to the ions’ dipole moments at each step of molecular dynamics by iterating them to self-consistency. The potential parameters are obtained by fitting to forces, stresses and energies calculated by density functional theory. The phase transition from perovskite to post-perovskite is predicted to take place at a pressure of 60 GPa at zero temperature. The potential reproduces well structural and thermodynamic properties as well as defects formation in a wide range of pressures, and therefore will be useful for the investigation of MgSiO₃ based materials in a geophysical context.