Computational Studies on Some Important Molecules
Wilfredo Credo Chung
Fukui Institute for Fundamental Chemistry, Kyoto University, Japan 606-8103 E-mail: [email protected]
In this talk, I will present a couple of molecular systems where we applied well-known theories in quantum mechanics both from a time-independent and time-dependent perspective in order to understand reaction mechanisms both in the ground and excited states:
1. We proposed and compared two intramolecular dissociation pathways of ethyl fluoroformate radical cation based on ground-state potential energy surfaces. [1,2]
The PES`s are good enough to explain relative heights of some of the mass spectral peaks of the electron ionization spectrum.
2. The relaxation of the low-lying excited states of 9H-adenine through conical intersections of the dissociative 1πσ* excited state with the lowest 1ππ* excited state and the electronic ground state was investigated with multireference electronic- structure calculations [3,4] and wave packet dynamics simulation [5]. Time- dependent wave packet simulations reveal an ultrafast relaxations dynamics of the optically-allowed lowest 1ππ* state driven by vibronic coupling between strongly coupled electronic states that add to our understanding of the origin of the intrinsic photostability of the building blocks of life.
3. The dynamics of the photoisomerization of a model protonated Schiff base of 9-cis retinal in isorhodopsin is investigated using nonadiabatic molecular dynamics simulation combined with ab initio quantum chemical calculations on-the-fly. [6] The photoinduced cis-trans isomerization of 9-cis retinal proceeds slower than that of its 11-cis analogue and at a lower quantum yield due mainly to an energetic barrier in the excited state.
I will also discuss some of our most recent research activities at FIFC.
References:
1. Chung, W. C.; Ignacio, E. W. Journal of Molecular Structure-Theochem 2004, 677, 97-104.
2. Chung, W. C.; Ignacio, E. W. Journal of Molecular Structure-Theochem 2005, 713, 153-159.
3. Chung, W. C.; Lan, Z. G.; Ohtsuki, Y.; Shimakura, N.; Domcke, W.; Fujimura, Y.
Physical Chemistry Chemical Physics 2007, 9, 2075-2084.
4. Hassan, W. M. I.; Chung, W. C.; Shimakura, N.; Koseki, S.; Kono, H.; Fujimura, Y.
Physical Chemistry Chemical Physics 2010,12, 5317-5328 .
5. Chung, W. C.; Markmann, A. G.; Shimakura, N.; Kono, H.; Domcke, W.; Fujimura, Y., In preparation.
6. Chung, W. C.; Ishida, T., Submitted.
