Canonical parallel tempering simulations of Arn–HCl clusters (n=1–12)

Parallel tempering simulations of the 13-center Lennard-Jones dipole-dipole cluster (μD=→0.5a.u.)

“…We observe this phenomena in some Ar n -HF and Ar n -HCl clusters, 60,61 but the fold in the heat-capacity surface that is visible at small values of D in Fig. This increase in the C V / k B surface is tied to the value of C V / k B at equipartition and to the relative softness of the potential energy along some degrees of freedom.…”

“…A typical example is the work on ͑HF͒ n clusters. [56][57][58][59][60][61][62][63][64][65][66][67] Most of our work has been focused around the Ar n -HF and Ar n -HCl systems where a number of interesting phenomena similar to those found in the isotropic systems have been observed. 51 On the other hand, the formulation of an accurate analytical potential-energy surface from highly precise ab initio calculations for the dimer can contain hundreds of terms.…”

“…53 Cartesian coordinates yield the simplest path-integral algorithms; however, it may be very inconvenient or impossible to set up a unique set of Cartesian axis to carry out quantum simulations. 61 The work on heterogeneous Lennard-Jones clusters establishes unequivocally the presence of impurities as the cause for the increase in thermodynamic complexity in the small clusters and the onset of solid-solid isomerizations. 54,55 Our group is among those that have begun to extend the set of theoretical tools the community has developed for Lennard-Jones clusters, to clusters bound by strong anisotropic interactions.…”