REFINED EMBEDDED-CLUSTER CALCULATIONS FOR TRAPPED HOLE BIPOLARONS IN BATIO3

Abstract

Embedded-quantum-cluster calculations are used to investigate the formation of hole-type bipolarons in BaTiO3. These simulations improve on our recent results because of the exact performance of geometry optimizations of the embedded quantum cluster. Moreover, ion relaxations and electron correlations have been treated consistently. The modelling of correlations includes Moller-Plesset perturbation theory to second order (MP2) and density functional theory (DFT) beyond the local density approximation. Both defect-induced crystal relaxations and electron correlation contributions are necessary in order to stabilize trapped hole bipolarons in BaTiO3.