Relativistic molecular spinors by generalized multiple scattering theory

A molecular one‐electron Dirac equation is derived by variation of a total energy density functional, whereby the one‐electron energies are ascribed a physical meaning. The multiple scattering formalism for molecular systems is relativistically generalized for the determination of molecular four‐component spinors. Optimal spinors and one‐electron energies for a finite basis set are derived by variation of a functional. The form of the secular equation is very similar to the nonrelativistic form. Using scattering theory, the quantities appearing in the secular equation are interpreted.