DAVYDOV SOLITON AND POLARONS IN MOLECULAR CHAINS - PARTIAL HAMILTONIAN DIAGONALIZATION

The energy of a Davydov soliton from a site-independent or D2 wave-fun ction ansatz is obtained in the discrete chain model by using a simula ted annealing approach to obtain the envelope of the soliton. Partial diagonalization [A. A. Eremko, Y. B. Gaididei, and A. A. Vakhnenko, Ph ys. Status Solidi B 127, 703 (1985)] of the Davydov Hamiltonian allows the soliton to be explicitly displayed in the Hamiltonian. The site-d ependent or D1 Davydov wave-function ansatz is examined variationally using the simulated annealing approach. This approach leads efficientl y to a minimum energy solution in the form of a uniform polaron state as required by translational symmetry. A simple form for the polaron s tate is displayed. We find no evidence for a minimum energy localized state such as is found from the more constrained D2 wave-function ansa tz. [S1063-651X(98)15111-5].