Ionic pseudopotential for semiconductors without cut-off parameter for core-repulsion with application to Si

An ionic pseudopotential for semiconductors is proposed, which consists of a set of continuous exponential functions. Introduced damping and amplitude parameters into the pseudopotential are to be treated as adjustable. The most important features of the proposed pseudopotential is that (1) it has no sharp cut-off parameter for the core-repulsion and (2) it is continuous and has continuous derivatives to arbitrary order. The proposed pseudopotential is applied to Si and the adjustable parameters are determined so as to be consistent with the Si crystal empirical pseudopotential of high quality by taking a valence electron dielectric screening effect into account. The effectiveness of the proposed ionic pseudopotential is discussed by (1) comparing the calculated ionic energy levels of Si with experiments, (2) checking the consistency between the ionic and crystal pseudopotentials for Si, and so on.