arXiv subjects

A. Lucke

Publications and source records attributed to A. Lucke.

4 recordsLinked to original sources

arXiv1999

Coherent nuclear motion in a condensed-phase environment: Wave-packet approach and pump-probe spectroscopy

A quantum-mechanical Gaussian wave-packet approach to the theoretical description of nuclear motions in a condensed-phase environment is developed. General expressions for the time-dependent reduced density matrix are given for a harmonic potential surface, and the exact quantum dynamics is found for a microscopic system-plus-bath model. Particular attention is devoted to the influence of initial correlations between system and bath for the outcome of a pump-probe experiment. We show that the standard factorized preparation, compared to a more realistic correlated preparation, leads to significantly different stimulated emission spectra at high temperatures. Recent experiments for the reaction center are analyzed using this formalism.

physics.chem-ph↗

arXiv1997

Is the direct observation of electronic coherence in electron transfer reactions possible?

The observability of electronic coherence in electron transfer reactions is discussed. We show that under appropriate circumstances large-amplitude oscillations can be found in the electronic occupation probabilities. The initial preparation of the system is of crucial importance for this effect, and we discuss conditions under which experiments detecting electronic coherence should be feasible. The Feynman-Vernon influence functional formalism is extended to examine more general and experimentally relevant initial preparations. Analytical expressions and path integral quantum dynamics simulations were developed to study the effects of various initial preparations on the observability of electronic coherence.

cond-mat↗

arXiv1996

Invaded cluster algorithm for Potts models

The invaded cluster algorithm, a new method for simulating phase transitions, is described in detail. Theoretical, albeit nonrigorous, justification of the method is presented and the algorithm is applied to Potts models in two and three dimensions. The algorithm is shown to be useful for both first-order and continuous transitions and evidently provides an efficient way to distinguish between these possibilities. The dynamic properties of the invaded cluster algorithm are studied. Numerical evidence suggests that the algorithm has no critical slowing for Ising models.

cond-mat↗

arXiv1995

Invaded cluster algorithm for equilibrium critical points

A new cluster algorithm based on invasion percolation is described. The algorithm samples the critical point of a spin system without a priori knowledge of the critical temperature and provides an efficient way to determine the critical temperature and other observables in the critical region. The method is illustrated for the two- and three-dimensional Ising models. The algorithm equilibrates spin configurations much faster than the closely related Swendsen-Wang algorithm.

cond-mat↗