First-principles study of multiferroic material PbVO under uniaxial pressure.

First-principles calculations are performed to simulate the tetragonal multiferroic material PbVO under uniaxial pressure. A first-order tetragonal to cubic structural phase transition takes place under uniaxial pressure of 1.2 GPa, which is accompanied by abruptly changes of the structural parameters, lattice volume, and atomic displacements. Comparative electronic structure calculations are performed for PbVO with the generalised gradient approximation (GGA) and the B3LYP hybrid functional. The hybrid functional drastically improves the band gap of the ground state of PbVO. The GGA and the B3LYP hybrid functional predict contradictory electronic structures for the high pressure cubic phase of PbVO. The results of the B3LYP hybrid functional calculation disprove the metallisation of PbVO under uniaxial pressure. The insulating electronic structure reproduced with B3LYP is consistent with recent experimental observations of semiconducting behaviour for the high pressure cubic phase of PbVO. [ABSTRACT FROM AUTHOR]