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Title: Nonempirical electron-correlation calculations on ALi/sub k/ and Ali/sub k+1//sup +/ clusters formed with elements from the second and third periods

Journal Article · · J. Struct. Chem. (Engl. Transl.); (United States)
OSTI ID:5820712

Several basic sets have been used (from 3-21 G/sub A//asterisk/ to DZHD + P/sub A/) with electron correlation in the Meller-Plesset MP3 approximation in nonempirical calculations on ALi/sub k+1//sup +/ and ALi/sub K+1//sup +/ lithium clusters (CLi/sub 2/, CLi/sub 3//sup +/, NLi/sub 3/, NLi/sub 4//sup +/, OLi/sub 2/, OLi/sub 3//sup +/, etc.) formed with elements from the second and third periods in the lowest singlet states. A study has been made on the effects of the approximation on the results. Several reference systems are used to show that the SCF/3-21G/sub A//asterisk/ approximation describes the lithide geometry satisfactorily, while MP3/DZHD + P/sub A/ gives a satisfactory description of the affinity of Ali/sub k/ for Li/sup +/. These approximations have been taken as optimal for calculations on the other compounds. The Li/sup +/ affinities are highest for NLi/sub 3/ and PLi/sub 3/ (90 and 84 kcal correspondingly) and decrease as A varies along the subgroups from the second to the third and the lower sp periods, as well as when A varies in each period from the middle to the start or end. The affinities of the analogous compounds for Na/sup +/ are less by 5-10 kcal than those for Li/sup +/. The values are compared with the proton affinities for the related hydrides AK/sub k/.

OSTI ID:
5820712
Journal Information:
J. Struct. Chem. (Engl. Transl.); (United States), Vol. 29:3; Other Information: Translated from Zh. Strukt. Khim.; 29: No. 3, 12-21(May-Jun 1988)
Country of Publication:
United States
Language:
English