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A quantum mechanics-molecular mechanics study of dissociative electron transfer : The methylchloride radical anion in aqueous solution
- Source :
- SORIANO, Alejandro ; SILLA, Estanislao ; TUÑÓN, Iñaki. A quantum mechanics-molecular mechanics study of dissociative electron transfer: The methylchloride radical anion in aqueous solution. En: Journal of Chemical Physics, 2002, vol. 116, no. 14, RODERIC. Repositorio Institucional de la Universitat de Valéncia, instname
- Publication Year :
- 2002
-
Abstract
- The dissociative electron transfer reaction CH3Cl+e−→CH3•+Cl− in aqueous solution is studied by using a QM/MM method. In this work the quantum subsystem (a methylchloride molecule plus an electron) is described using density functional theory while the solvent (300 water molecules) is described using the TIP3P classical potential. By means of molecular dynamics simulations and the thermodynamic integration technique we obtained the potential of mean force (PMF) for the carbon–chlorine bond dissociation of the neutral and radical anion species. Combining these two free energy curves we found a quadratic dependence of the activation free energy on the reaction free energy in agreement with Marcus’ relationship, originally developed for electron transfer processes not involving bond breaking. We also investigated dynamical aspects by means of 60 dissociative trajectories started with the addition of an extra electron to different configurations of a methylchloride molecule in solution. The PMF shows the existence of a very flat region, in which the system is trapped during some finite time if the quantum subsystem quickly losses its excess kinetic energy transferring it to the solvent molecules. One of the most important factors determining the effectiveness of this energy transfer seems to be the existence of close contacts (hydrogen bonds) between the solute and the solvent. Estanislao.Silla@uv.es Ignacio.Tunon@uv.es
- Subjects :
- Aqueous solution
Chemistry
General Physics and Astronomy
Thermodynamic integration
Free radicals
Molecular dynamics method
Organic compounds
Dissociation
Charge exchange
Negative ions
Digital simulation
Kinetic energy
UNESCO::FÍSICA::Química física
Molecular dynamics
Electron transfer
Quantum mechanics
Molecule
Density functional theory
Physical and Theoretical Chemistry
Potential of mean force
Physics::Chemical Physics
FÍSICA::Química física [UNESCO]
Subjects
Details
- Database :
- OpenAIRE
- Journal :
- SORIANO, Alejandro ; SILLA, Estanislao ; TUÑÓN, Iñaki. A quantum mechanics-molecular mechanics study of dissociative electron transfer: The methylchloride radical anion in aqueous solution. En: Journal of Chemical Physics, 2002, vol. 116, no. 14, RODERIC. Repositorio Institucional de la Universitat de Valéncia, instname
- Accession number :
- edsair.doi.dedup.....0932c38e6fd27456c6f39b86b73d96c1