SEARCH Articles Figures Tables Configuration interaction frozen core approximation Electronic structure methods frozen core Energy frozen-core valence Frozen core approach Frozen core approximation, combination with Frozen core potentials Frozen-core Hartree-Fock Frozen-core Hartree—Fock calculations Frozen-core approximation Frozen-core approximation correlation Frozen-core basis sets Frozen-core orbitals Frozen-core spin-orbit Hamiltonian Frozen-core treatment Pseudopotentials frozen-core Space frozen core approximation Spin-free frozen-core approximation The Frozen-Core Approximation