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

We calculate electron momentum densities of various crystalline solids by employing the linear-muffin-tin-orbital (LMTO) method. We use three levels of approximation to the LMTO: the simplest atomic sphere approximation (ASA), the ASA with overlap correction, and the full-potential (FP) LMTO. Although the band energies calculated using the ASA and the FP-LMTO are practically the same, there is a noticeable difference in the electron momentum densities which is not cured by making a simple overlap correction to the ASA-LMTO method.