A two reference determinant version of the distinguishable cluster with singles and doubles (DCSD) has been developed. We have implemented the two determinant distinguishable cluster (2D-DCSD) and the corresponding traditional 2D-CCSD method in a new open-source package written in Julia called ElemCo.jl. The methods were benchmarked on singlet and triplet excited states of valence and Rydberg character, as well as for singlet-triplet gaps of diradicals. It is demonstrated that the distinguishable cluster approximation improves the accuracy of 2D-CCSD.
Cite
@article{arxiv.2401.11935,
title = {Two Determinant Distinguishable Cluster},
author = {Thomas Schraivogel and Daniel Kats},
journal= {arXiv preprint arXiv:2401.11935},
year = {2024}
}