title: Quantum chemistry study of H+(H2O)8: a global search for its isomers by the scaled hypersphere search method, and its thermal behavior.
abstract: The structures of the protonated water cluster H+(H2O)8 have been globally explored by the scaled hypersphere search method. On the Hartree-Fock potential energy surface 174 isomers were found, among which 168 were computed to be minima at the B3LYP/6-31+G** level, and their energies were further refined at the level of MP2/6-311++G(3df,2p). The global minimum on the potential energy surface computed at the B3LYP/6-31+G** level shows a cagelike structure with the "Eigen" motif, while the lowest-free-energy isomer has a five-membered-ring structure at 170 K and a chain form at 273 K. The present results are well in line with previous experimental findings. In addition, the ADMP (atom-centered density matrix propagation) simulation indicates that the extra proton in the lowest-free-energy isomer (170 K), which has a five-membered ring and the "Zundel" feature, is often in an asymmetrical hydrogen bond.
authors: Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
authors: Yi
authors: Y
authors: Luo
authors: Satoshi
authors: S
authors: Maeda
authors: Koichi
authors: K
authors: Ohno
mesh_terms: D000465:Algorithms; D004735:Energy Transfer; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D007536:Isomerism; D011522:Protons; D011789:Quantum Theory; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D011522:Protons; D014867:Water; D006859:Hydrogen