Relativistic density-functional theory based on effective quantum electrodynamics

TL;DR

This paper develops a relativistic density-functional theory based on effective quantum electrodynamics that includes vacuum polarization effects without explicit photon degrees of freedom, providing a tractable approach for atomic and molecular calculations.

Contribution

It introduces a new relativistic density-functional framework based on effective QED Hamiltonian, incorporating vacuum polarization effects in a computationally manageable way.

Findings

Formulation of a Kohn-Sham scheme similar to non-relativistic DFT

Analysis of charge-conjugation symmetry and scaling properties of density functionals

Derivation of the no-pair Kohn-Sham scheme as an approximation

Abstract

A relativistic density-functional theory based on a Fock-space effective quantum-electrodynamics (QED) Hamiltonian using the Coulomb or Coulomb-Breit two-particle interaction is developed. This effective QED theory properly includes the effects of vacuum polarization through the creation of electron-positron pairs but does not include explicitly the photon degrees of freedom. It is thus a more tractable alternative to full QED for atomic and molecular calculations. Using the constrained-search formalism, a Kohn-Sham scheme is formulated in a quite similar way to non-relativistic density-functional theory, and some exact properties of the involved density functionals are studied, namely charge-conjugation symmetry and uniform coordinate scaling. The usual no-pair Kohn-Sham scheme is obtained as a well-defined approximation to this relativistic density-functional theory.