************OWARI COMPLEX SEMINAR LII*************

Title : Multi-Scale Methods for the Investigation 
of Biological Structures and Processes

Speaker : Dr.Marcus Elstner

Affiliation : Karlsruhe Institute of Technology (KIT), Germany

Date : Fri. Apr. 12, 17:00 pm (Almost two hours)

Place : 4F Seminar Room, Graduate School of Information Science

Abstract :
In the last years, we have combined ab initio quantum 
chemistry and density functional theory (DFT) methods 
with semi-empirical (SCC-DFTB), empirical force field 
and continuum electrostatic methods in so called Multi-
Scale approachesin order to study biological structures 
and processes on different time and length scales. This 
includes also the use of QM/QM/MM methods as well as 
polarizable force fields and a variety of sampling 
methods, which allow to overcome the limitations of 
direct molecular dynamics simulations. One major field 
of application concerns the rhodopsin family of proteins. 
Here, we have studied in particular the mechanisms of 
color tuning as well as proton transport pathways in 
Bacteriorhodopsin. We used a variety of spectroscopic 
methods like UV/vis, IR, Raman, NMR in order to clarify 
details of the molecular structures, not resolved by 
experiment. A second major field of application is 
concerned with electron/hole transfer in complex 
molecular systems. Due to the immense system size of 
several hundreds of atoms, which have to be treated 
quantum mechanically, we have developed a coarse-
grained quantum/classical methodology within the framework 
of time-dependent DFT. This methodology allows to describe 
the dynamics of the electronic system coupled to the 
dynamics of DNA or proteins in water solvent and shows, 
that solvent fluctuations are a major driving force 
of hole transfer. Currently, we extend this methodology 
towards organic electronics applications.

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