LARGE STRUCTURAL AND MAGNETIC PHASE-STABILITY OF VS AND VSE

Using the full potential (LAPW) band structure method, a detailed inve stigation of the structural and magnetic phase stability of VS and VSe has been performed. In full accordance with experiment, the MnP-struc ture was found to be the equilibrium phase for VS at low temperature. The changes in the electronic structure that accompany the phase trans ition from the orthorhombic MnP-structure to the hexagonal NiAs-struct ure is monitored using the dispersion relations, the density of states curves as well as the electronic charge density distribution. For VSe in the NiAs-structure the magnetic phase diagram as a function of the hexagonal lattice parameters a and c has been determined. In agreemen t with experiment, the antiferromagnetic phase was found to be energet ically the most favourable one among the para-, ferro- and anti-ferrom agnetic phases.