SEARCH Articles Figures Tables Effective Hamiltonian Effective Hamiltonian formalism projection operator Effective Hamiltonian mapping operators Effective Hamiltonian time-independent operator Effective Hamiltonians Hamiltonian operator Hamiltonian operator Stark effect Hamiltonian operator Zeeman effect Mapping operators Hermitian effective Hamiltonian Operating effectiveness Operational Effectiveness Operational Effects Semiempirical Hamiltonians, effective operators Wave operator, effective Hamiltonians