Some useful odds and ends from the n-electron valence state perturbation theory.
The n-electron valence state perturbation theory makes use of zero-order wave functions whose energies are endowed with a direct physical interest, describing various processes occurring in the active space (removal/addition of one or two electrons, electronic excitations). It is shown that the zero-order energies related to the process of removal of an electron from the active space provide a reasonable and cheap approximation to the vertical ionization potentials. The zero-order energies referring to the process of an electronic excitation within the active space can also provide a first approximation to electronic transition energies, provided that a careful choice of the active molecular orbitals is performed. Test calculations have been carried out on the molecules N2 and H2CO.
Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Ferrara , Via Fossato di Mortara 17, 44121 Ferrara, Italy.
Celestino
C
Angeli
Renzo
R
Cimiraglia
D004583:Electrons; D005557:Formaldehyde / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry; D011789:Quantum Theory
D005557:Formaldehyde; D009584:Nitrogen