Quantum versus Semiclassical Description of Selftrapping Anharmonic Effects.pdfVIP

Quantum versus Semiclassical Description of Selftrapping: Anharmonic Effects 1 2 3 S. Raghavan ,A. R. Bishop , and V. M. Kenkre 1 International Centre for Theoretical Physics, 34100 Trieste, Italy and 9 Rochester Theory Center for Optical Science and Engineering, 9 ∗ 9 Department of Physics Astronomy, University of Rochester, Rochester NY 14627 , 1 b 2 Los Alamos National Laboratory, Los Alamos NM 87545 e F 3 Center for Advanced Studies and Dept. of Physics Astronomy 3 University of New Mexico, Albuquerque NM 87131 1 v 8 5 0 2 Abstract 0 9 9 / Selftrapping has been traditionally studied on the assumption that quasipar- t a m ticles interact with harmonic phonons and that this interaction is linear in - d the displacement of the phonon. To complement recent semiclassical studies n o c of anharmonicity and nonlinearity in this context, we present below a fully : v i quantum mechanical analysis of a two-site system, where the oscillator is de- X r scribed by a tunably anharmonic potential, with a square well with infinite a walls and the harmonic potential as its extreme limits, and wherein the inter- action is nonlinear in the oscillator displacement. We find that even highly anharmonic polarons behave similar to their harmonic counte