OCCSFrD

Open-shell Coupled Cluster using a Spin-Free Diagrammatic approach (OCCSFrD) is a Python package to derive and solve equations for spin-adapted and spin-free single- and multi-reference coupled cluster methods for open shell molecular electronic structure. OCCSFrD has been used to implement our Normal-Ordered Exponential Coupled Cluster (NOECC) method for treating dynamic correlation in high-spin doublets and triplets, and open-shell singlets.