Structural Characterization of Sulfur-Containing Water Clusters Using a Density-Functional Based Tight-Binding Approach

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 120; no. 45; pp. 9089 - 9100
• Main Authors: Korchagina, Kseniia A, Simon, Aude, Rapacioli, Mathias, Spiegelman, Fernand, Cuny, Jérôme
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 17-11-2016
• Subjects: Chemical Sciences; or physical chemistry; Theoretical and
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/acs.jpca.6b08251

A global optimization search of low-energy isomers is carried out to investigate the structural and stability properties of sulfur-containing water clusters, including both (H2O) n SO4 2– and (H2O) n H2SO4 aggregates. The systematic optimization algorithm involves a combination of parallel-tempering molecular dynamics and periodic gradient-driven quenches with energy and energy-gradient calculations performed using the Self-Consistent-Charge Density-Functional based Tight-Binding (SCC-DFTB) scheme. Comparisons with new MP2 and DFT calculations on the smallest systems and previous ab initio investigations of the literature show that the SCC-DFTB approach provides a fairly accurate description of both neutral and ionic species, comparable to that of DFT. Structural and stability features of larger sulfur-containing clusters, with up to 20 water molecules, are also determined using the SCC-DFTB scheme. The interest of this work is 2-fold: (i) the benchmark on small species demonstrates the ability of SCC-DFTB to describe complex potential energy landscapes involving hydrogen-bonds and proton transfers; (ii) it opens the way to the study of large clusters that can hardly be performed within ab initio approaches.