Projected Wave-Field Approach to the Many-Electron Problem in Solids

Abstract
The orthogonalized plane wave (O. P. W.) method for treating electrons in solids is generalized to the many-body problem. The core electrons are assumed to be dynamically independent of the valence electrons. Using a field-theoretical approach, a model wave field is introduced whose valence projection is the valence wave field of the physical system. When an appropriate choice is made for the model Hamiltonian, the rapid convergence of the O. P. W. method is incorporated in the many-body perturbation expansion.