Theoretical Study On Stable Structures Of Ethanol-Water Clusters

As aggregates of finite number of atoms or molecular at the microscopic level, clusters exhibit novel geometries,electronic properties as well as widely potential applications. The study of atom or molecule clusters can not only help to make more understanding of native properties of clusters, but also speed learning of properties of solid body. More and more interests have been abstracted for studying clusters both experimentally and theoretically. Recently years, the faint force between molecules gradually became the focus of clusters studies, hydrogen-bond as the typical represent of faint force has abstracted more and more researchers'interests.In this paper, C₂H₅OH(H₂O)_n (n=1-9) clusters were calculated at the B3LYP/6-311++G(2d,2p)//B3LYP/6-311++G(d,p) level. The computed properties characterizing C₂H₅OH(H₂O)_n (n=1-9) clusters include optimal structures, structural parameters, hydrogen bonds, binding energies, average hydrogen bond strength, NBO charge distributions, cluster growth rhythm, and so on. Results show that the transition from two-dimensional cyclic to three-dimensional cage structures occurs at n=5. Moreover, the lowest energy structure of C₂H₅OH(H₂O)_n (n=6) cluster is probably thought as magic number structure by using properties of the second order difference of binding energy, formation energy, and energy gap. Finally, in order to probe into the nature of hydrogen bond, properties of the lowest energy structures for C₂H₅OH(H₂O)_n (n=2-9) clusters were compared with those of pure water clusters (H₂O)_n (n=3-10), and results show that hydrogen bonds forming between water molecules in the former are similar to those in the latter.Based on the study of the B3LYP method, we found that it's very meaningful to investigate the properties of the cyclic C₂H₅OH(H₂O)_n (n=1-5) clusters. Therefore, several properties have been analyzed at the MP2/6-311++G(2d,2p)//MP2/6-311++G(d,p) level, include optimal structures, structural parameters, hydrogen bonds, Charge distributions, binding energies, cooperative effects, and so on. Results show that cooperative effects and hydrogen bonding strengths increase with the increasing cluster sizes.