Quasirelativistic electronic $T$-matrix for the short-range perturbation

Abstract

Exact $T$-matrix for the delta-function short-range perturbation of the (3+1)-Dirac equation has been derived. Separability of the potential in the angular momentum representation is used. A characteristic equation for the $T$-matric poles determining the bound and resonance states has been obtained. The calculated $T$-matrix determines transport properties of the narrow-gap and zero-gap semiconductors.