Investigation of the relative stabilities of various allotropic phases of elemental tellurium under pressure and their interconversion paths by electronic structure calculations and crystal structure analyses

Elemental tellurium adopts a number of different structures under pressure. The relative stabilities of these allotropes and the interconversion between them were examined on the basis of first principles electronic band structure calculations with and without external pressure. The relative stabilities of the allotropes were also analyzed by estimating the overall strength of covalent bonding on the basis of the Te-Te overlap populations determined from tight-binding electronic structure calculations. The crystal structures of the allotropes were analyzed to determine how one form can transform into another form under pressure. Our study leads to the energy profile of tellurium as a function of pressure consistent with experiment, shows that the relative stabilities of the allotropic phases of Te are mainly governed by the overall strength of covalent bonding, and that all the allotropes are intimately related in structure, and one form can be readily converted to another form under pressure via a simple interconversion path