Ab initio method for calculating total cross sections

A method for calculating total cross sections, without formally including non-elastic channels, is presented. The idea is to use a one channel T-matrix variational principle with a complex correlation function. The derived T-matrix is therefore not unitary: elastic scattering is calculated from |T|2, but total scattering is derived from the imaginary part of T using the optical theorem. The method is applied to the spherically symmetric model of electron-hydrogen scattering. No spurious structure arises; results for σel and σtotal are in excellent agreement with calculations of Callaway and Oza. The method has wide potential applicability