Conformational equilibria of peroxynitrous acid in water: A first-principles molecular dynamics study

Citation
K. Doclo et U. Rothlisberger, Conformational equilibria of peroxynitrous acid in water: A first-principles molecular dynamics study, J PHYS CH A, 104(27), 2000, pp. 6464-6469
Citations number
31
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHYSICAL CHEMISTRY A
ISSN journal
10895639 → ACNP
Volume
104
Issue
27
Year of publication
2000
Pages
6464 - 6469
Database
ISI
SICI code
1089-5639(20000713)104:27<6464:CEOPAI>2.0.ZU;2-1
Abstract
An aqueous solution of peroxynitrous acid has been studied using first-prin ciples molecular dynamics simulations based on density functional theory. T he relative Helmholtz energies of different conformers have been determined via thermodynamic integration with constraints. At contrast to the gas pha se, only two conformers, a cis and a trans isomer, are present in solution and their relative Helmholtz energy is enhanced with respect to the gas pha se. The average structural properties of the two conformational forms on th e other hand are very close to the respective gas phase values. The interco nversion pathway between the two conformers has: been determined, and the H elmholtz energy profile for the isomerization reaction in solution is prese nted. The rotational barrier is calculated to be substantially higher than in gas phase due to a strong rearrangement of the solvent during the reacti on. The structure of the transition state can only be described correctly w hen the solvent is taken explicitly into account. Our calculations indicate that the cis form is the dominant species in aqueous solution at ambient t emperatures.