J. Phys. Chem. A, 111 (41), 10345 -10352, 2007. 10.1021/jp0722657 S1089-5639(07)02265-7
Web Release Date: August 3, 2007

Copyright © 2007 American Chemical Society

Thermodynamics of Atomic Clusters Using Variational Quantum Hydrodynamics

Sean W. Derrickson and Eric R. Bittner*

Department of Chemistry and Center for Materials Chemistry, University of Houston, Houston, Texas 77204

Received: March 21, 2007

In Final Form: May 30, 2007

Abstract:

Small clusters of rare-gas atoms are ideal test cases for studying how quantum delocalization affects both the thermodynamics and the structure of molecular scale systems. In this paper, we use a variational quantum hydrodynamic approach to examine the structure and dynamics of (Ne)n clusters, with n up to 100 atoms, at both T = 0 K and for temperatures spanning the solid-to-liquid transition in bulk Ne. Finite temperature contributions are introduced to the grand potential in the form of an "entropy" potential. One surprising result is the prediction of a negative heat capacity for very small clusters that we attribute to the nonadditive nature of the total free-energy for very small systems.


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