Dual vibration configuration interaction (DVCI). An efficient factorization of molecular Hamiltonian for high performance infrared spectrum computation

Solution method: The Ak decomposition (Gershgorn and Shavitt, 1968) completed by a meaningful error evaluation namely the residue ||HX−EX|| minimized along iterations for specific targets given in input. The approximation space is generated in the same time as the residual vectors computed on the fly thanks to an adapted choice of excitations shaped on the Hamiltonian operator.