OJPC> Vol.5 No.4, November 2015

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Kholmirzo T. Kholmurodov^1,2, Sagille A. Ibragimova², Pavel P. Gladishev², Anatoly V. Vannikov³, Alexey R. Tameev³, Tatyana Yu. Zelenyak²

¹Frank Laboratory of Neutron Physics, JINR, Dubna, Russia.
²Dubna International University, Dubna, Russia.
³A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia.

The perovskites with general formula ABX₃ have been widely used as for materials with their unique properties (ferroelectric, piezoelectric, dielectric, catalytic and so on). Hybrid organolead halide perovskites are a class of semiconductors with ABX₃ (X = Cl, Br, and I) structures consisting of lead cations in 6-fold coordination (B site), surrounded by an octahedron of halide anions (X site, face centered) together with the organic components in 12-fold cub octahedral coordination. These hybrid perovskites have a direct band gap, a large absorption coefficient as well as high charge carrier mobility that represent a very attractive characteristic of cost-effective solar cells. Basically, these crystals are inorganic solids of CaTiO₃ type held together by bonds that are either ionic or partially ionic and partially covalent. In spite of the partially covalent character of the Ti-O bond, the system is modeled by a two-body central force interatomic potential (the form of the Vashishta and Rahman interatomic potential), which has been used successfully for many materials with a perovskite structure. In the present work using molecular dynamics (MD) simulation method we investigate the dynamical and structural behavior of CaTiO₃ perovskite at normal pressure and temperature conditions. The MD calculations were performed on a system of 16,000 particles (3200Ca + 3200Ti + 96,00O), initially in an orthorhombic-Pbnm structure. The orthorhombic MD box had edges L_x = 53.4 Å, L_y = 53.4 Å and L_z = 61.12 Å, which provided a density matching the experimental value of ρ = 4 g/cm³. Starting with this structure and using proposed interatomic potentials the MD system stabilizes at room temperature in its initial configuration. The aim of the present study to explore the effect of potential function representations on structural equilibrium properties for the perovskite models including hybrid halide ones outlined above. Concerning the perovskite equilibrium state we elucidate the role of potential function modification on the atomic pair correlation and structural re-organization. The details of the interatomic potential representation have to be crucially important for obtaining of correct analysis data in crystallic, liquid and amorphous phases including perovskite systems.

Perovskites, Halides, Potential Functions, Structural Properties, MD Simulations

Kholmurodov, K. , Ibragimova, S. , Gladishev, P. , Vannikov, A. , Tameev, A. and Zelenyak, T. (2015) Molecular Dynamics Simulations of Perovskites: The Effect of Potential Function Representation on Equilibrium Structural Properties. Open Journal of Physical Chemistry, 5, 110-121. doi: 10.4236/ojpc.2015.54012.