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Updated: May 12, 2026
Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Systematic study of structural and thermodynamic properties of HCl(H2O)n clusters from semiempirical replica exchange
1Department of Chemistry and Biochemistry, University of California, San Diego 9500 Gilman Drive, La Jolla, California 92093, USA.
Abstract:
The structural and thermodynamic properties of HCl(H2O)n clusters with n = 4-10 are studied using Born-Oppenheimer replica exchange molecular dynamics simulations with the PM3-MAIS semiempirical Hamiltonian. Independently of the cluster size, the simulations predict that HCl exists in the dissociated form in all low-energy isomers. Different local structures are identified within the clusters due to the presence of the dissociated proton, including Zundel, Eigen, Eigen-like, H7O3(+), and intermediate Zundel-Eigen configurations. As the cluster size increases, several groups of isomers are identified, whose relative stabilities vary as a function of temperature. A detailed analysis of the heat capacity indicates that the melting behavior of HCl(H2O)n clusters is strongly size-dependent. In particular, melting is observed in clusters with n = 7-10 in the temperature range T = 100-150 K. By contrast, melting is not observed in clusters with n = 4-6. Minimum energy structures for HCl(H2O)n clusters with n = 11-15 and n = 21 are also characterized.
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