Investigation of the electronic structure and phonon anharmonicity in<i>β</i>- and<i>γ</i>-NbH

Abstract

First-principles electronic-structure and total-energy calculations have been performed for NbH in the \ensuremath{\beta}- and \ensuremath{\gamma}-phase structures. Lattice constants, bulk moduli, and heats of formation have been calculated and found to be in excellent agreement with measured values. We have made detailed ``frozen-phonon'' calculations investigating the effect of anharmonic couplings on the optical vibrations of hydrogen and its isotopes in NbH.