%0 Journal Article %1 publ8713381 %A Werner, Hans Joachim %A Knowles, Peter J. %D 1990 %J Theor. Chim. Acta %K chemie werner from:alexanderdenzel Configuration theoretische stuttgart interaction,Diatomic theochem molecules,Non-variational,Variational %N 3 %P 175–187 %R 10.1007/BF01112867 %T A comparison of variational and non-variational internally contracted multiconfiguration-reference configuration interaction calculations %U http://dx.doi.org/10.1007/BF01112867 %V 78 %X The internally contracted multiconfiguration-reference configuration interaction (CMRCI) method and several non-variational variants of this method (averaged coupled pair approximation (ACPF), quasidegenerate variational perturbation theory (QD-VPT), linearized coupled pair many electron theory (LCPMET)) have been employed to compute potential energy functions and other properties for a number of diatomic molecules (F2, O₂, N₂, CN, CO) using large basis sets and full valence CASSCF reference wavefunctions. In most cases the variational CMRCI wavefunctions yield more accurate spectroscopic constants than any of the employed non-variational methods. Several basis sets are compared for the N₂ molecule. It is found that atomic natural orbital (ANO) contractions led to significant errors in the computedr e , ω e , andD e values. %@ 2016042239061

@article{publ8713381, abstract = {The internally contracted multiconfiguration-reference configuration interaction (CMRCI) method and several non-variational variants of this method (averaged coupled pair approximation (ACPF), quasidegenerate variational perturbation theory (QD-VPT), linearized coupled pair many electron theory (LCPMET)) have been employed to compute potential energy functions and other properties for a number of diatomic molecules (F2, O₂, N₂, CN, CO) using large basis sets and full valence CASSCF reference wavefunctions. In most cases the variational CMRCI wavefunctions yield more accurate spectroscopic constants than any of the employed non-variational methods. Several basis sets are compared for the N₂ molecule. It is found that atomic natural orbital (ANO) contractions led to significant errors in the computedr e , ω e , andD e values.}, added-at = {2019-03-01T15:49:37.000+0100}, author = {Werner, Hans Joachim and Knowles, Peter J.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2fee56cdf7dd0500adedebbbd400461aa/theochem}, doi = {10.1007/BF01112867}, interhash = {82c6ec0225d8a181046db588c22c2703}, intrahash = {fee56cdf7dd0500adedebbbd400461aa}, isbn = {2016042239061}, issn = {00405744}, journal = {Theor. Chim. Acta}, keywords = {chemie werner from:alexanderdenzel Configuration theoretische stuttgart interaction,Diatomic theochem molecules,Non-variational,Variational}, number = 3, pages = {175–187}, timestamp = {2019-03-01T14:49:37.000+0100}, title = {{A comparison of variational and non-variational internally contracted multiconfiguration-reference configuration interaction calculations}}, url = {http://dx.doi.org/10.1007/BF01112867}, volume = 78, year = 1990 }