Ab-initio study of phase transition and momentum density in PbTe

Abstract

In this article, the high-pressure structural phase transition and electron momentum density in PbTe have been studied by means of first-principles total energy calculations which are based on the linear combination of atomic orbitals method within generalized gradient approximation. It is observed that the stable phase of PbTe is rocksalt (B1) type and it transforms to an orthorhombic Pnma (B27, FeB type) structure at 6.77 GPa. Further, structural phase transition from the Pnma phase to the cesium chloride (B2) phase has been observed at 13.04 GPa. The anisotropies in theoretical directional Compton profiles indicate larger occupied states along the [100] direction. On the basis of equal-valence-electron-density profiles, it is found that PbTe shows less ionicity as compared to PbS and PbSe.

Keywords:

• phase transition
• electron momentum density
• IV–VI semiconductor; LCAO method

Acknowledgements

This work is financially supported by the CSIR, New Delhi through the grant no. 03(1205/12EMR-II). GS is grateful to Prof. B.K. Sharma, University of Rajasthan, Jaipur for encouragement and discussion.