Electron momentum density and band structure calculations of α- and β-GeTe

We have measured isotropic experimental Compton profile of alpha-GeTe by employing high energy (662 key) gamma-radiation from a Cs-137 isotope. To compare our experiment, we have also computed energy bands, density of states, electron momentum densities and Compton profiles of alpha- and beta-phases of GeTe using the linear combination of atomic orbitals method. The electron momentum density is found to play a major role in understanding the topology of bands in the vicinity of the Fermi level. It is seen that the density functional theory (DFT) with generalised gradient approximation is relatively in better agreement with the experiment than the local density approximation and hybrid Hartree-Fock/DFT. (C) 2011 Elsevier Ltd. All rights reserved.