Multi-reference perturbation theory with Cholesky decomposition for the density matrix renormalization group

摘要

We present a second-order N-electron valence state perturbation theory(NEVPT2) based on a density matrix renormalization group (DMRG) reference wavefunction that exploits a Cholesky decomposition of the two-electron repulsionintegrals (CD-DMRG-NEVPT2). With a parameter-free multireference perturbationtheory approach at hand, the latter allows us to efficiently describe staticand dynamic correlation in large molecular systems. We demonstrate theapplicability of CD-DMRG-NEVPT2 for spin-state energetics of spin-crossovercomplexes involving calculations with more than 1000 atomic basis functions. Wefirst assess in a study of a heme model the accuracy of the strongly- andpartially-contracted variant of CD-DMRG-NEVPT2 before embarking on resolving acontroversy about the spin ground state of a cobalt tropocoronand complex.