Construction of linearly independent non-orthogonal AGP states

TL;DR

This paper introduces a method to construct linearly independent non-orthogonal AGP states, enabling efficient evaluation of matrix elements and a new AGP-based configuration interaction approach for flexible accuracy-cost trade-offs.

Contribution

It presents a novel way to construct linearly independent non-orthogonal AGP states, simplifying calculations and enabling a new AGP-based CI method.

Findings

Allows rewriting geminal replacement models as linear combinations of non-orthogonal AGPs

Enables efficient evaluation of matrix elements

Introduces an AGP-based selective configuration interaction method

Abstract

We show how to construct a linearly independent set of antisymmetrized geminal power (AGP) states, which allows us to rewrite our recently introduced geminal replacement models as linear combinations of non-orthogonal AGPs. This greatly simplifies the evaluation of matrix elements and permits us to introduce an AGP-based selective configuration interaction method, which can reach arbitrary excitation levels relative to a reference AGP, balancing accuracy and cost as we see fit.