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Multiconfiguration wavefuntions for the lowest (ππ*) excited states of ethylene

✍ Scribed by Charles F. Bender; Thom.H. Dunning Jr.; Henry F. Schaefer III; William A. Goddard III; William J. Hunt

Publisher
Elsevier Science
Year
1972
Tongue
English
Weight
848 KB
Volume
15
Category
Article
ISSN
0009-2614

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✦ Synopsis

Ab initio calculations have been carried out for the T(3B,u) and V('BIu) states of ethylene in a planar nuclear conf@ration.

A "double-zeta" gaussian basis, augmented by diffuse functions, was used. A wide variety of configuration interaction wavefunctions (including as many as 1605 configurations), optimized by the iterative natural orbital method, were computed. The ulcuiations predict the IB,,, state to lie 3.8-4.1 eV above the 3B,, state. The spatial extent of the triplet state is that of a normal valence state with (x2) = 12 bohr'. The singlet state, on the other hand, is found to be quite diffuse or Rydberg-like, Cr2) = 35 bohr*; electron correlation was found to decrease Cr*) by 30% from the Hartree-Fock value (52 bob?). This result is not consistent with simple notions concerning n-electron theory.

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