A highly accurate interatomic potential for LaMnO3 perovskites with temperature-dependence of structure and thermal properties

Abstract

ABO3-type perovskites LaMnO3 is a colossal magnetoresistance material that undergoes an orthorhombic-rhombohedral phase transition as the temperature increases. Phase transition determines its structural properties and thermal conductivity that are important in industrial application. Structural transition is reflected mainly in Mn-O bond lengths and Mn-O-Mn angles between MnO6 octahedrons for Jahn-Teller effect during this progress and traditional born–mayer (BM) model has difficulty in description of structural distortion and thermal properties. In this paper, a new classic interatomic potential model for LaMnO3 was developed within the framework of bond valence (BV) theory. First-principles and intelligent optimization algorithm were used to fit the parameters, enabling the study of temperature-dependent structures by accurate large-scale molecular dynamics (MD) simulations. Calculated structural distortions by our model and thermal properties calculated with equilibrium molecular dynamics (EMD) method accorded with the experimental values within a reasonable error, and had higher accuracy than traditional born-mayer model. These results provided further insight about temperature-depended phase transition and further performance mining of LaMnO3. Most importantly, our potential model showed better accuracy than traditional potential model and is applicablefor all crystal materials with perovskite structures.