Seniority based energy renormalization group (Ω-ERG) approach in quantum chemistry: Initial formulation and application to potential energy surfaces

摘要: Abstract This investigation combines the concept of seniority number Ω (defined as total singly occupied orbitals in a determinant) with energy renormalization group (ERG) approach to obtain lowest-energy electronic states on molecular potential surfaces. The proposed Ω-ERG method uses Slater determinants that are ordered according ascending order. In procedure, active system consists M (N-electron) and K additional complement (complement-system). Among m represent target interest (target-states), thus m ≤ M. environment Full Configuration Interaction (FCI) reservoir from which complement-states being selected. goal procedure is FCI quality an iterative way at reduced computational cost. general, convergence rate energies towards values depends M, thus, notation Ω-ERG(m, M) used. It found can be very effective for calculating (ground excited) when sufficiently large sweeps We find fastest observed M > m. performance describing strongly correlated systems has been illustrated by examining bond-breaking processes N2, H8, H2O C2. present, proof-of-principle study yields encouraging results multiple surfaces near CI quality.