Passing the one-billion limit in full configuration-interaction (FCI) calculations

Abstract

Full configuration-interaction calculations have been carried out using more than one-billion determinants. Such large eigenvalue calculations are possible because of advances in the direct CI technology and in the iterative technique used to solve the eigenvalue equations. The CPU time per direct CI iteration varies approximately linearly with the dimension of the matrix from one million to more than one billion. One direct CI iteration is found to take about 1.2-1.4 min per million determinants on an IBM 3090/VF.