SEARCH Articles Figures Tables Hamiltonian Douglas-Kroll, second-order Hamiltonian effective second-order spin Hamiltonian second-order effective Hamiltonian second-order iterated Hamiltonian second-order perturbation theory Second-Order Foldy-Wouthuysen Operator Pauli Hamiltonian Some Applications of Second-order Many-body Perturbation Theory with a Moller-Plesset Reference Hamiltonian Spin Hamiltonian second order