Correlating the Antisymmetrized Geminal Power Wave Function

TL;DR

This paper explores the antisymmetrized geminal power wave function as a reference for advanced correlation methods to better describe strong pairing correlations in superconductivity.

Contribution

It proposes using the antisymmetrized geminal power wave function as a reference state for sophisticated correlation techniques.

Findings

Provides a framework for improving correlation descriptions

Highlights limitations of the antisymmetrized geminal power

Suggests pathways for enhanced quantitative accuracy

Abstract

Strong pairing correlations are responsible for superconductivity and off-diagonal long range order in the two-particle density matrix. The antisymmetrized geminal power wave function was championed many years ago as the simplest model that can provide a reasonable qualitative description for these correlations without breaking number symmetry. The fact remains, however, that the antisymmetrized geminal power is not generally quantitatively accurate in all correlation regimes. In this work, we discuss how we might use this wave function as a reference state for a more sophisticated correlation technique such as configuration interaction, coupled cluster theory, or the random phase approximation.