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 applicable for all crystal materials with perovskite structures.