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Multiple solutions of the single-reference coupled-cluster method

✍ Scribed by Leszek Meissner; Anna Balková; Rodney J. Bartlett

Publisher
Elsevier Science
Year
1993
Tongue
English
Weight
696 KB
Volume
212
Category
Article
ISSN
0009-2614

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✦ Synopsis

The nonlinear coupled-cluster (CC) equations possess several solutions. They describe various excited states as long as they contain a contribution from the reference function. We study the additional solutions of the single-reference CC equations and demonstrate that unlike the ground state, the approximate solution for excited states in general does not satisfy the cluster condition nor the standard proof of extensivity. For such states that makes the CC approximation poorer than that for the analogous CI.

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