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Titolo:
Hydrogen bonding and the dipole moment of hydrofluorocarbons by density functional theory
Autore:
Cabral, BJC; Guedes, RC; Pai-Panandiker, RS; de Castro, CAN;
Indirizzi:
Complexo Interdisciplinar Univ Lisboa, Dept Quim & Bioquim, P-1649003 Lisbon, Portugal Complexo Interdisciplinar Univ Lisboa Lisbon Portugal P-1649003 Portugal Complexo Interdisciplinar Univ Lisboa, Ctr Fis Mat Condensada, P-1649003 Lisbon, Portugal Complexo Interdisciplinar Univ Lisboa Lisbon Portugal P-1649003 Portugal Univ Lisbon, Fac Ciencias, Dept Quim & Bioquim, P-1749016 Lisbon, PortugalUniv Lisbon Lisbon Portugal P-1749016 ioquim, P-1749016 Lisbon, Portugal Univ Lisbon, Fac Ciencias, Ctr Ciencias Mol & Mat, P-1749016 Lisbon, Portugal Univ Lisbon Lisbon Portugal P-1749016 & Mat, P-1749016 Lisbon, Portugal
Titolo Testata:
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
fascicolo: 19, volume: 3, anno: 2001,
pagine: 4200 - 4207
SICI:
1463-9076(2001)3:19<4200:HBATDM>2.0.ZU;2-L
Fonte:
ISI
Lingua:
ENG
Soggetto:
1,1-DICHLORO-1-FLUOROETHANE HCFC 141B; 1,1,1,2-TETRAFLUOROETHANE HFC 134A; THERMAL-CONDUCTIVITY; MOLECULAR-PROPERTIES; DIELECTRIC-CONSTANT; TOTAL ENERGIES; AB-INITIO; DISSOCIATION ENERGIES; ELECTRON CORRELATION; INTERNAL-ROTATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
64
Recensione:
Indirizzi per estratti:
Indirizzo: Cabral, BJC Complexo Interdisciplinar Univ Lisboa, Dept Quim & Bioquim, Ave Prof Gama Pinto 2, P-1649003 Lisbon, Portugal Complexo Interdisciplinar Univ Lisboa Ave Prof Gama Pinto 2 Lisbon Portugal P-1649003
Citazione:
B.J.C. Cabral et al., "Hydrogen bonding and the dipole moment of hydrofluorocarbons by density functional theory", PHYS CHEM P, 3(19), 2001, pp. 4200-4207

Abstract

Recent measurements of the dielectric permittivity of hydrofluorocarbons in the liquid phase have allowed calculation of the dipole moments in a liquid environment. These values were based on Kirkwood theory, and were significantly greater than the corresponding gas phase dipole moments. In order to understand some features suggesting possible hindered rotation of the molecules in the liquid, density functional and self-consistent-reaction-fieldcalculations for a series of HFC molecules including CHF2CF3 (HFC-125), CH2FCF3 (HFC-134a), CH3CF3 (HFC-143a), CH2F2 (HFC-32) and CHF2CH3 (HFC-152a) are reported. Particular emphasis has been given to the calculation of dimerisation energies, rotational potentials, polarisabilities and dipole moments. We discuss hydrogen bonding in hydrofluorocarbon dimers and the relationship between the structure and charge distribution of the dimers and the dipole moment in the liquid predicted by relative permittivity measurements. For HFC-32 we have calculated the average dipole moment in small clusters (n = 2-10). The structure of the clusters has been determined by density functional theory optimisations (n = 2-6) and Monte Carlo simulations (n = 2-10). The average dipole moment of the HFC-32 decamer is 2.35 D, which represents a 17% increase relative to the free monomer (2.0 D). We find that theenhancement of the monomer dipole induced by hydrogen bonding in HFC-32 clusters is much less pronounced in comparison with the considerable increase(50%) observed in water clusters.

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Documento generato il 08/04/20 alle ore 07:45:30