# Geminal-Based Configuration Interaction

## TL;DR

This paper introduces a geminal-based configuration interaction method that enhances the accuracy of AGP wave functions, especially for systems with strong pairing correlations, by constructing an excitation manifold that generalizes standard CI.

## Contribution

It develops a geminal CI approach that improves upon AGP and can incorporate more general geminal wave functions, advancing the modeling of strongly correlated systems.

## Key findings

- Geminal CI outperforms AGP in the reduced BCS Hamiltonian.
- The method reduces to standard CI when AGP simplifies to a single determinant.
- It naturally extends to more general geminal wave functions.

## Abstract

The antisymmetrized geminal power (AGP) wave function has a long history and considerable conceptual appeal, but in many situations its accuracy is wanting. Here, we consider a form of configuration interaction (CI) based upon the AGP wave function and taking advantage of its killing operators to construct an excitation manifold. Our geminal CI reduces to standard single-determinant--based CI in the limit in which AGP reduces to a single determinant. It substantially improves upon AGP in the reduced BCS Hamiltonian, which serves as a prototype for the kinds of strong pairing correlations relevant in Bardeen-Cooper-Schrieffer--style superconductivity. Moreover, our geminal CI naturally generalizes to add correlation to more general geminal-based wave functions than AGP.