Generalised non-muffin-tin multiple scattering theory

The author presents a derivation of generalised multiple scattering (MS) theory for finite systems such as molecules, atomic clusters and nuclei. It eliminates the need for the muffin-tin approximation (MTA) in the MS methods commonly used in quantum chemistry (e.g., in the X alpha -SCW method). It is completely separable and does not contain the near-field error common to previous attempts to construct a generalised theory. The generalised equations are identical to the well known MTA MS equations, but with the correct definition of the cellular T matrix.