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Titolo:
Mechanism of acid dissociation in water clusters: Electronic structure studies of (H2O)(n)HX (n = 4, 7; X = OH, F, HS, HSO3, OOSO2H, OOH center dot SO2)
Autore:
Smith, A; Vincent, MA; Hillier, IH;
Indirizzi:
Univ Manchester, Dept Chem, Manchester M13 9PL, Lancs, England Univ Manchester Manchester Lancs England M13 9PL M13 9PL, Lancs, England
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY A
fascicolo: 8, volume: 103, anno: 1999,
pagine: 1132 - 1139
SICI:
1089-5639(19990225)103:8<1132:MOADIW>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
AB-INITIO; MOLECULAR-DYNAMICS; BISULFITE ION; ENERGY; HCL; SIMULATIONS; POTENTIALS; HEXAMER; H2S;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
43
Recensione:
Indirizzi per estratti:
Indirizzo: Hillier, IH Univ Manchester, Dept Chem, Oxford Rd, Manchester M13 9PL, Lancs, England Univ Manchester Oxford Rd Manchester Lancs England M13 9PL and
Citazione:
A. Smith et al., "Mechanism of acid dissociation in water clusters: Electronic structure studies of (H2O)(n)HX (n = 4, 7; X = OH, F, HS, HSO3, OOSO2H, OOH center dot SO2)", J PHYS CH A, 103(8), 1999, pp. 1132-1139

Abstract

High-level electronic structure calculations have been carried out to identify stationary structures on the potential energy surface of a number of acids in water clusters, with 4 or 7 solvent molecules. The calculations employed a 6-311++g** basis with correlation at the MP2 and DFT (B3LYP) levels. Both DFT and a smaller basis set tended to favor the zwitterionic, compared to the unionized, structures. The cooperative nature of the ionization process was especially evident, with single and double layers of three watermolecules separating the ionized groups and actively participating in ionization. For the pure water clusters, both (H2O)(5) and (H2O)(8) had similarrelative energies for unionized, zwitterionic, and transition-state structures, showing that a range of structures and ionization mechanisms can occur in bulk water. For HF and H2S, the relative energetics and stationary structures showed ionization to be more favorable in the larger clusters. The trend of earlier transition states for the stronger acids was identified for HF, H2S, and H2SO3.

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Documento generato il 04/12/20 alle ore 06:22:06