Hamiltonian polyelectronic atom

The Hamiltonian, H, for polyelectronic systems (atom or molecule) is given by Eq. (1.110). It can be divided into three terms HR, a term intrinsic to the radiation field, HM, a term intrinsic to the molecular field, and Hh a term for the interaction between the radiation and the molecular fields. The term //, is further divided into first and second order terms of the vector potential, A, for the quantified operators, p-A = A p, using Vvl = 0. 

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