ISSN:
1573-935X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Conclusions Our calculations of the specific correlation energy including all singly and doubly excited configurations and unlinked clusters shows that it is constant for even polyenes with up to 12 carbon atoms. The contribution to the energy from interorbital correlations and higher excitations, inclusion of which involves most difficulty when describing correlation effects on the basis of a consistent use of the variational approach, is appreciable. Though in the shortest polyenes the correlation energy is almost entirely due to intraorbital correlations, their contribution for dodecahexaene is only slightly more than half the correlation energy. Higher excitations do not contribute as much as the interorbital correlations in these shells. However, their relative contribution increases with chain length and for longer chains calculations of the correlation energy are incomplete without them. In particular, when the number of atoms in the system tends to infinity, practically all the correlation energy arises from higher excitations. The calculations were carried out at the Computer Center, Institute of Cybernetics, Academy of Sciences of the Ukrainian SSR, on a BéSM-6 computer using our own suite of FORTRAN programs.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01001698
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