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Titolo:
CALCULATION OF THE AQUEOUS SOLVATION FREE-ENERGY OF THE PROTON
Autore:
TAWA GJ; TOPOL IA; BURT SK; CALDWELL RA; RASHIN AA;
Indirizzi:
NCI,FREDERICK CANC RES & DEV CTR,FREDERICK BIOMED SUPERCOMP CTR,SAIC FREDERICK,POB B FREDERICK MD 21702 UNIV TEXAS,DEPT CHEM RICHARDSON TX 75083 BIOCHEMCOMP INC TEANECK NJ 07666
Titolo Testata:
The Journal of chemical physics
fascicolo: 12, volume: 109, anno: 1998,
pagine: 4852 - 4863
SICI:
0021-9606(1998)109:12<4852:COTASF>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
DENSITY-FUNCTIONAL THEORY; BOUNDARY-ELEMENT METHOD; SMALL WATER CLUSTERS; MOLECULAR-INTERACTIONS; AB-INITIO; VIBRATIONAL-SPECTRA; DIELECTRIC MODEL; EXCHANGE-ENERGY; CONTINUUM MODEL; DIPOLE-MOMENT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
91
Recensione:
Indirizzi per estratti:
Citazione:
G.J. Tawa et al., "CALCULATION OF THE AQUEOUS SOLVATION FREE-ENERGY OF THE PROTON", The Journal of chemical physics, 109(12), 1998, pp. 4852-4863

Abstract

The value of the proton hydration free energy, Delta G(hyd)(H+) has been quoted in the literature to be from -252.6 to -262.5 kcal/mol. In this article, we present a theoretical model for calculating the hydration free energy of ions in aqueous solvent and use this model to calculate the proton hydration free energy, Delta G(hyd)(H+), in an effortto resolve the uncertainty concerning its exact value. In the model we define Delta G(hyd)(H+) as the free energy change associated with the following process: Delta G[H+(gas)+ H2nOn(aq)-->H+(H2nOn)(aq)], where the solvent is represented by a neutral n-water cluster embedded in a dielectric continuum and the solvated proton is represented by a protonated n-water cluster also in the continuum. All solvated species are treated as quantum mechanical solutes coupled to a dielectric continuum using a self consistent reaction field cycle. We investigated the behavior of Delta G(hyd)(H+) as the number of explicit waters of hydration is increased from n = 1 to n = 6. As n increases from 1 to 3, thehydration foe energy decreases dramatically. However, for n = 4-6 thehydration foe energy maintains a relatively constant value of -262.23kcal/mol. These results indicate that the first hydration shell of the proton is composed of at least four water molecules, The constant value of the hydration free energy for n greater than or equal to 4 strongly suggests that the proton hydration free energy is at the far lower end of the range of values that have been proposed in the literature. (C) 1998 American Institute of Physics.

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Documento generato il 02/12/20 alle ore 15:00:55