Evaluation of Linear Thermal Expansion Coefficients of Perovskite Oxides Using Ab-initio Molecular Dynamics with Small Cell Sizes for Materials Design

Abstract

Calculations of linear thermal expansion coefficients have been carried out using ab-initio molecular dynamics with a small cell containing only ten atoms, which is a suitable cell size for materials design. The perovskite oxides of SrTiO 3 , BaZrO 3 , LaNiO 3 , CMgO 3 , CCaO 3 , and LaCoO 3 were selected as the reference materials for comparison between calculated and experimental values. The calculated lattice constants were in good agreement with the experimental values. The thermal expansion coefficients of the six oxides, including LaCoO 3 in the complex spin state, were evaluated from the temperature dependence of the lattice constants. There was reasonable agreement between the calculated and experimental values. Our results clearly proved that it is possible to obtain linear thermal expansion coefficients by ab-initio molecular dynamics, even with the use of a small cell for the calculations.