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Thermodynamics of water octamer in a uniform electric field.

Hernández-Rojas J, González BS, James T, Wales DJ

Departamento de Física Fundamental II, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain.

We study the water octamer in a uniform electric field using the all-exchanges parallel tempering Monte Carlo method in the canonical ensemble. The heat capacity, quenched energy configurations, and the order parameter Q(4) are employed to understand the phase changes observed as a function of temperature and the strength of the applied electric field. At a low field strength of 0.1 V A(-1) a solidlike to liquidlike "melting" transition is detected. The corresponding heat capacity peak appears around 206 K, where Q(4) shows a significant change of slope. For E>/=0.5 V A(-1) such features are absent. However, at E=0.5 V A(-1) we find a solidlike to solidlike transition between cubic and extended structures around T approximately 25 K.

Published 19 December 2006 in J Chem Phys, 125(22): 224302.
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