QED approach to valence-hole excitation in closed shell systems

TL;DR

This paper develops an ab initio QED method using the two-time Green function approach to accurately calculate valence-hole excitation energies in closed shell systems, incorporating various quantum corrections.

Contribution

It introduces a novel QED framework with a redefined vacuum state for valence-hole excitations, connecting Green functions to energy corrections in a consistent way.

Findings

Derived first-order corrections including self-energy, vacuum polarization, and photon exchange.

Established equivalence with many-body perturbation theory in the Breit approximation.

Proposed a spectral representation confirming excitation energy poles.

Abstract

An ab initio QED approach to treat a valence-hole excitation in closed shell systems is developed in the framework of the two-time-Green function method. The derivation considers a redefinition of the vacuum state and its excitation as a valence-hole pair. The proper two-time Green function, whose spectral representation confirms the poles at valence-hole excitation energies is proposed. An contour integral formula which connects the energy corrections and the Green function is also presented. First-order corrections to the valence-hole excitation energy involving self-energy, vacuum polarization, and one-photon-exchange terms are explicitly derived in the redefined vacuum picture. Reduction to the usual vacuum electron propagators is given that agrees in the Breit approximation with the many-body perturbation theory expressions for the valence-hole excitation energy.