[Todos] Seminarios DQIAyQF/ INQUIMAE. Lunes 24 de Julio, 13h

[sara elizabeth bari]

Seminarios del Dpto. de Química Inorgánica, Analítica y Química Física / INQUIMAE

FCEyN - Universidad de Buenos Aires

http://www.qi.fcen.uba.ar/es

 

 2006

  

  

Lunes 24 de Julio, 13.00h
Aula Seminarios, DQIAyQF- INQUIMAE

Ciudad Universitaria, Pab. II, Piso 3 

 

 

Prof. Nicola Marzari

Department of Materials Science and Engineering
Massachusetts Institute of Technology

 
"Excited states in transition-metal complexes: from electron-transfer reactions to biomimetic catalysis"


A general approach to calculate the free energy surfaces for electron-transfer reactions is presented, based on first-principles molecular dynamics of the active centers and their surrounding medium.The excitation energy corresponding to the transfer of an electron at any given ionic configuration (the Marcus energy gap) is accurately assessed within ground-state density-functional theory via a novel penalty functional for oxidation-reduction reactions that appropriately acts on the electronic degrees of freedom alone. The self-interaction error intrinsic to common exchange-correlation functionals is also corrected by the same penalty functional. The diabatic free-energy surfaces are then constructed from umbrella sampling on large ensembles of configurations. As a paradigmatic case study, the self-exchange reaction between ferrous and ferric ions in water is studied in detail, but this same formalism applies to a wide variety of reaction, from electron-transfer in photosynthesis to optical absorption under the conditions of intervalence charge transfer.

Finally, we'll highlight the importance of generalized, selfconsistent GGA+U approaches in describing spin multiplicities and potential energy surfaces in catalytic reactions involving transition-metal complexes

 

 

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