Atomistic modelling of BaTiO₃based on first-principles calculations

Abstract

Interatomic potentials are determined in the framework of a shell model used to simulate the structural instabilities, dynamical properties, and phase transition sequence of BaTiO 3 . The model is developed from first-principles calculations by mapping the potential energy surface for various ferroelectric distortions. The parameters are obtained by performing a fit of interatomic potentials to this energy surface. Several zero-temperature properties of BaTiO 3 , which are of central importance, are correctly simulated in the framework of our model. The phase diagram as a function of temperature is obtained through constant-pressure molecular dynamics simulations, showing that the non-trivial phase transition sequence of BaTiO 3 is correctly reproduced. The lattice parameters and expansion coefficients for the different phases are in good agreement with experimental data, while the theoretically determined transition temperatures tend to be too small.

Quantitative analysis of the first-principles effective Hamiltonian approach to ferroelectric perovskites

“…Results for a 7×7×7 periodic supercell (1715 ions plus 1715 shells which are additional degrees of freedom) were reported in Ref. 4. It was shown that the cubic-tetragonal-orthorhombicrhombohedral phase sequence is correctly reproduced.…”

“…In this Section we describe the effective Hamiltonian that we have constructed using the shell model for BaTiO 3 of Tinte et al 4 as our target system. The form of the effective Hamiltonian is identical to that proposed by Zhong et al, 3 except that the inhomogeneous strain variables found to be unimportant in that study are not included here.…”

“…We use the total energies computed with the BaTiO 3 "shell model" interatomic potential of Tinte et al 4 to construct an effective Hamiltonian, and compare the computed transition temperatures with those obtained in direct classical simulations for the "shell model" system. In this comparison, we completely eliminate errors of Types I, IV and V, and can easily make errors of Type III negligible.…”

The ReaxFF Polarizable Reactive Force Fields for Molecular Dynamics Simulation of Ferroelectrics

“…For example the First-Principles-based effective Hamiltonian approach [4,5] gives the correct order of phases (cubic, tetragonal, orthorhombic, rhombohedral) but low transition temperatures (290 K, 230 K, and 197 K) compared with experimental values (403 K, 278 K, 183 K), see for example [2]. The non-linear Oxygen polarizability shell model [6] has been used with MD to calculate the phase transition temperatures. This model also gives the phase transitions in the correct order but with low transition temperatures (190 K; 120 K and 90 K).…”

Molecular-dynamics investigation on polarization retention of barium titanate nanofilm arising from ordered oxygen vacancy

“…For the molecular-dynamics (MD) framework, an isotropic core-shell model [10] developed from first principle [12] is employed in the present study to depict the interactions among ions. The said model has been successfully employed to depict the phase transition sequence that depends on temperature [10], size dependence of film [13] and wire [14], surface properties and influence of epitaxial strain on ferroelectric behavior [11] and, most importantly, the point-defect formation energy [6], which is significant in a point-defect system.…”