A graphical symmetric group approach for a spin adapted full configuration interaction:partitioning of a configuration graph into sets of closed-shell and open-shell graphs

摘要

We developed a spin adapted full configuration interaction (FCI) method which was expected to be effective for parallel processing.The graphical symmetric group approach (GSGA) was employed,where a configuration graph was partitioned into several sets of closed-shell and open-shell graphs.The configuration state functions (CSFs) bearing the same number of closed-shells and open-shells were assembled in a configuration group.The graphical approach provided a number to identify each CSF in a sequential order within the group.Combination of this partitioning and an intermediate configuration-driven algorithm in calculating the so-called a vectors allowed us to use symbolic coupling constants.Furthermore,this combination made it easy to implement an efficient algorithm suitable to task-distributed parallel procedure for evaluating sigma vectors.A program was written and some test calculations were carried out with high parallel efficiency.The largest size of FCI used 10 million CSFs (20 million determinants).