The energy landscape of protonated water clusters H(+)(H2O)n is thoroughly explored at the first-principle level using a hierarchical search methodology. In particular, the distinct configurational isomers of OSS2 empirical potential for n = 5-9 are uncovered and archived systematically using an asynchronous genetic algorithm and are subsequently refined with first-principle calculations. Using the OSS2 model, quantitative agreements in the thermal properties between Monte Carlo and harmonic superposition approximation (HSA) highlighted the reliability of the latter approach for the study of small- to medium-sized protonated water clusters. From the large sets of collected isomers, finite temperature behavior of the clusters can be efficiently examined at first-principle accuracy with the use of HSA. From the results obtained, evidence of structural changes from single-ring to treelike (n = 5-7) and multi-ring to single-ring structures (n = 7-9) is observed, as expected for the empirical model. Finally, the relevance of these findings to recent experimental data is discussed.
We propose a multiscale method to explore the energy landscape of water clusters. An asynchronous genetic algorithm is employed to explore the potential energy surface (PES) of OSS2 and TTM2.1-F models. Local minimum structures are collected on the fly, and the ultrafast shape recognition algorithm was used to remove duplicate structures. These structures are then refined at the B3LYP/6-31+G* level. The number of distinct local minima we found (21, 76, 369, 1443, and 3563 isomers for n = 4-8, respectively) reflects the complexity of the PES of water clusters.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.