First-Principle Calculation of Elastic Compliance Coefficients for BiFeO₃

Abstract

The elastic compliance coefficients of PbTiO ₃ with/without geometric optimization are firstly calculated by using density-functional theory (DFT) under different exchange correlation functions. It is found that the best results are not obtained by LDA/CA-PZ and optimized structure although these induce the nearest lattice constants to experimental ones, however, the results of PbTiO ₃ without geometry optimization under GGA/PW91 function are in great consistent with the experimental data. Based on the same calculating method of PbTiO ₃ , the elastic compliance coefficients for BiFeO ₃ are obtained. And the data are compared with previous results predicted by fitting experimental data to Landau-type phenomenological theory, which possessing the difference of an order of magnitude with our data.

Keywords:

• BiFeO₃
• elastic compliance coefficients
• first-principle theory

PACS:

• 30.15.A-
• 62.20.Dc
• 81.05.-t

Acknowledgments

The authors are grateful for the financial supports by the 973 program (2007CB616910), the NSFCs (50572021, 10774036, and 60876055), the NSFs of Hebei Province (E2008000620, E2008000631), State Education Ministry (207013) and foundation of Hebei University.