Full-potential linear-muffin-tin-orbital calculation of electron momentum densities of solids

We calculate electron momentum densities of various crystalline solids by e mploying the linear-muffin-tin-orbital (LMTO) method. We use three levels o f approximation to the LMTO: the simplest atomic sphere approximation (ASA) , the ASA with overlap correction, and the full-potential (FP) LMTO. Althou gh the band energies calculated using the ASA and the FP-LMTO are practical ly the same, there is a noticeable difference in the electron momentum dens ities which is not cured by making a simple overlap correction to the ASA-L MTO method.