The effective quasiparticle potential in molecules and solids

Abstract

Using many-body Green function theory it can be shown that there is a single-particle Schrödinger equation containing an effective potential, whose eigenvalues give the quasiparticle excitations, and from which the ground state energy of the system can be found. This theory is applied to diatomic molecules and it is found that in general the effective potential is in between the Hartree-Fock and Wigner-Seitz potentials. The Wigner-Seitz potential is valid at large interatomic separations, corresponding to the Heitler-London limit.