PASSING THE ONE-QUADRILLION LIMIT IN FCI EXTRAPOLATIONS ON A PERSONAL-COMPUTER

An efficient algorithm for the full configuration interaction (FCI) on a personal computer is presented. Selected configuration interaction and second-order perturbation theory (PT) are combined to approach the . full-CI limit. Comparison was made to existing full-CI benchmarks. A test calculation of NH, symmetrical dissociation shows that the runni ng time for finding the correlation energy with an accuracy of 0.1 kca l/mol is just 5 min on an IBM 486DX2-66 PC, As another example, the ap proximate full-CI calculations of the HF dimer in the (4s2p1d/2s1p) an d the (4s3p/d/2s1p) basis sets have been carried our. The ground stale of(HF), produces 3 x 10(14) and 4 x 10(15) determinants, respectively .