Multiple solutions of coupled-cluster equations for PPP model of [10]annulene

Abstract

Multiple (real) solutions of the CC equations (corresponding to the CCD, ACP and ACPQ methods) are studied for the PPP model of [10]annulene, C_{10}H_{10}. The long-range electrostatic interactions are represented either by the Mataga--Nishimoto potential, or Pople's R^{-1} potential. The multiple solutions are obtained in a quasi-random manner, by generating a pool of starting amplitudes and applying a standard CC iterative procedure combined with Pulay's DIIS method. Several unexpected features of these solutions are uncovered, including the switching between two CCD solutions when moving between the weakly and strongly correlated regime of the PPP model with Pople's potential.

5 pages, 4 figures, RevTeX4

References in corpus (1)

• Electronic correlation in cyclic polyenes. Behavior of approximate coupled-pair theories for large rings

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• Second-order electronic correlation effects in a one-dimensional metal