Linearized Coupled Cluster Correction on the Antisymmetric Product of 1 reference orbital Geminals

TL;DR

This paper introduces a Linearized Coupled Cluster correction based on an AP1roG reference state, improving the accuracy and robustness of molecular dissociation and spectroscopic calculations compared to perturbation methods.

Contribution

The paper develops a novel LCC correction method on an AP1roG reference, enhancing computational reliability over existing perturbation-based approaches.

Findings

LCC correction yields spectroscopic constants in excellent agreement with reference data.

The method is more robust and reliable than perturbation theory-based corrections.

Effective for diatomic dissociation and hydrogen chain simulations.

Abstract

We present a Linearized Coupled Cluster (LCC) correction based on an Antisymmetric Product of 1 reference orbital Geminals (AP1roG) reference state. In our LCC ansatz, the cluster operator is restricted to double and to single and double excitations as in standard single-reference CC theory. The performance of the AP1roG-LCC models is tested for the dissociation of diatomic molecules (C$_2$ and F$_2$), spectroscopic constants of the uranyl cation (UO$_2^{2+}$), and the symmetric dissociation of the H$_{50}$ hydrogen chain. Our study indicates that an LCC correction based on an AP1roG reference function is more robust and reliable than corrections based on perturbation theory, yielding spectroscopic constants that are in very good agreement with theoretical reference data.