Douglas-Kroll-Hess AIMP molecular Hamiltonian

2 Douglas-Kroll-Hess AIMP molecular Hamiltonians 

In the Douglas-Kroll-Hess spin-free relativistic Hamiltonians (second-order and third-order) [11,13], the T andF operators in Eq. (4) are 

According to Hess [38], the integrals involving these operators are computed in momentum space using spectral representations (resolution of the identity) in the primitive molecular basis set. 

In order to produce the DKH-AIMP Hamiltonian, the approximation of operators that is adopted now, which corresponds to Eq. (12) in the case of CGWB-AIMP, is  

The ingredients of the spin-free DKH-AIMP relativistic Hamiltonians are available for the transition metal elements Sc to Hg (DKH-2) [12,37,40] as well as for the lanthanide and actinide elements (DKH-3) [14,41]. 

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