Stuttgart 2012 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 37: Atomic clusters

A 37.3: Vortrag

Donnerstag, 15. März 2012, 15:00–15:15, V57.05

First-order corrections and structural information in semiclassical Gaussian approximations to the Boltzmann operator for clusters of atoms — •Holger Cartarius¹ and Eli Pollak² — ¹1. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart, Germany — ²Chemical Physics Department, Weizmann Institute of Science, 76100 Rehovot, Israel

Gaussian approximations to the Boltzmann operator have proven themselves in recent years as useful tools for the study of the thermodynamic properties of rare gas clusters. They are, however, not necessarily correct at very low temperatures. We introduce a numerically cheap frozen Gaussian approximation to the imaginary time propagator with a width matrix especially suited for the dynamics of clusters [1] and investigate its first-order correction to diagnose the quality of the approximation [2]. The strength of the correction to the Gaussian partition function monitored as a function of the temperature indicates that the results of the Gaussian propagator become questionable below a certain temperature, however, thermodynamic henomena such as structural transformations occur in a temperature range for which the Gaussian approximation is predicted to be accurate.

To study transformations or dissociation effects of rare gas clusters for increasing temperature information about the structure is essential. We show how structural information can be extracted from the Gaussian imaginary time propagator.

[1] H. Cartarius, E. Pollak, J. Chem. Phys. 134, 044107 (2011)

[2] H. Cartarius, E. Pollak, Chem. Phys., in press (2011)