Some Useful Odds and Ends From the n-Electron Valence State Perturbation Theory
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- 作者：Celestino Angeli ; Renzo Cimiraglia
- 刊名：Journal of Physical Chemistry A
- 出版年：2014
- 出版时间：August 21, 2014
- 年：2014
- 卷：118
- 期：33
- 页码：6435-6439
- 全文大小：210K
- ISSN：1520-5215
文摘
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.