Intramolecular Excitation Dynamics in a Thermalized Chain. II. Formation of Autolocalized States in a Chain with Free Ends

Abstract

V. N. KADAKTSEV et al.: Intramolecular Excitation Dynamics in a Chain (11) 155 phys. stat. sol. (b) 147, 155 (1988) Subject classification: 71.45 Institute for Physico-Technologicul Research, Moscow1) Intramolecular Excitation Dynamics in a Thermalized Chain 11. Formation of Autolocalized States in a Chain with Free Ends2) BY V. N. KADANTSEV, L. N. LUPICHEV, and A. V. SAVINA numerical study of the Davydov soliton dynamics in a thermalized unclosed molecular chain with asymmetric exciton-phonon interaction is carried out. The effect of thermal vibrations in the scope of the quantum-mechanical model is taken into account. When initiating the excitation at the free end of the chain, the soliton transport is shown to be able to occur at temperatures close to 300 K only. In this case the soliton formation is dependent on which of the end molecules in the chain is excited first.

Finite-temperature two-state small-polaron dynamics: averaged Hamiltonian approach

“…Therefore, if the system parameters S and B fall into that part of parameter space lying below the symmetry-breaking boundaries, the semiclassical approximation is satisfactory and small-polaron dynamics are well described in terms of the discrete non-linear Schrödinger equation. For the present two-site problem, it finally results in a non-linear evolution equation for the transition probability (16). According to [11], the dynamics of the system, as described by that equation, exhibit a self-trapping transition which, depending on the values of S and B, may be achieved in two different ways.…”

“…This is the purpose of this paper in which we study how temperature modifies the self-trapped states and the conditions for their occurrence. In our study of the temperature effect we use a variational method referred to as the averaged Hamiltonian approach introduced by Davydov [9] and subsequently used extensively in the study of the temperature stability of molecular solitons [16][17][18]. In the following section we introduce our model and apply the variational approach, leading to specific conditions for the temperature dependence of the self-trapped state.…”

Effects of quantum lattice fluctuations on multiquanta Davydov-like solitons in a molecular chain

“…This especially concerns its applicability at physiological (T ∼ 300 K) temperatures. For that reason, different thermalization schemes were utilized in order to simulate soliton dynamics and to estimate the lifetime of the soliton at finite temperatures [10][11][12][13][14][15][16][17][18]. The results are rather different, and sometimes mutually quite opposite.…”

“…The results are rather different, and sometimes mutually quite opposite. Thus, while some workers find that thermal fluctuations destabilize the soliton, causing its finite lifetime to be too short to be relevant in realistic conditions [10,11,17,18], others find that thermal effects even support soliton creation and its stability [13,16].…”