Free energy changes in water clusters

Glen L Holden, University of Rhode Island


Free energy changes and other thermodynamic properties have been determined for classical TIP4P water clusters for aggregrate sizes 2 ≤ n ≤ 20 using Monte Carlo methods. The pairwise monomer interactions (PMI) are represented by Lennard-Jones and Coulombic potentials and the free energies, enthalpies and entropies are calculated as a function of temperature and cluster size. Temperature dependent heat capacity curves have provided the diagnostic for the observed phase changes in the processes considered. By examining the fine structure in the free energy changes as a function of cluster size, processes n=7 and n=11 have been found to be particularly stable. A set of new postulates have been articulated on the dipole orientations across atomic centers with hydrogen bonded interactions and in the geometric subspaces of certain clusters. These dipole orientations have been found to significantly influence the observed thermodynamic properties. The free energy changes and heat capacity curves for the encapsulation of a hydrogen molecule by TIP4P water clusters have also been studied at 1 bar pressure over a range of temperatures.

Subject Area

Physical chemistry|Molecular physics

Recommended Citation

Glen L Holden, "Free energy changes in water clusters" (2010). Dissertations and Master's Theses (Campus Access). Paper AAI3451835.