Geminal replacement models based on AGP

TL;DR

This paper explores various AGP-based correlation models for strongly correlated electrons, demonstrating their equivalence and introducing a new J-CI method that achieves high accuracy in pairing Hamiltonian energies.

Contribution

It shows the equivalence of different AGP-based correlator representations and introduces the J-CI method with linearly independent metrics for improved energy calculations.

Findings

J-CI achieves excellent accuracy in pairing Hamiltonian energies.

Different AGP-based correlator representations are equivalent in a seniority-conserving regime.

The method uses number operators with curvilinear metrics to distinguish Hilbert space regions.

Abstract

The antisymmetrized geminal power (AGP) wavefunction has a long history and is known by different names in various chemical and physical problems. There has been recent interest in using AGP as a starting point for strongly correlated electrons. Here, we show that in a seniority-conserving regime, different AGP based correlator representations based on generators of the algebra, killing operators, and geminal replacement operators are all equivalent. We implement one representation that uses number operators as correlators and has linearly independent curvilinear metrics to distinguish the regions of Hilbert space. This correlation method called J-CI, provides excellent accuracy in energies when applied to the pairing Hamiltonian.