Equation-of-motion Coupled-cluster singles, doubles and(full) triples for doubly ionized and two-electron-attached states: A Computational implementation

TL;DR

This paper details the implementation of an advanced equation-of-motion coupled-cluster method for calculating doubly ionized and two-electron attached states, including new algorithmic variants, within the Q-CHEM software.

Contribution

The paper introduces a computational implementation of EOM-CCSDT for DIP and DEA states, including both double and single precision algorithms, integrated into Q-CHEM.

Findings

Implementation available in upcoming Q-CHEM release

Demonstrated pilot application on $CH_2$ molecule

Includes programmable expressions for DIP and DEA states

Abstract

We present our computational implementation of the equation-of-motion (EOM) coupled-cluster (CC) singles, doubles, and triples (SDT) method for computing doubly ionized (DIP) and two-electron attached (DEA) states within Q-CHEM. These variants have been implemented within both the (conventional) double precision (DP) and the single precision (SP) algorithms and will be available in the upcoming major release of {\sl Q-CHEM}. We present here the programmable expressions and some pilot application of $CH_2$ for DIP and DEA EOM-CCSDT.