Abstract/Summary

We investigated the structure and the thermodynamic properties of small water clusters with the nested sampling computational technique, using two different water models, the coarse-grained mW (up to 25 molecules) and the flexible version of the TIP3P (up to 16 molecules). With mapping the entire potential energy landscape of the clusters, we calculated the heat capacity curves, located the structural transitions and identified those local minima basins which contribute the most to the total partition function. We found that in case of the mW model, trends in first-order-like and continuous-like transitions can be very well matched to the characteristics of the landscape: cluster sizes with fewer and narrower local minima basins show a sharper ’melting’ peak on the heat capacity curve. Trends in case of the TIP3P model were not easily assigned to changing occupation of basins, and the contribution of local minima were negligible, except for n = 7, 15 and 16.