Charge localization phenomena in synthetic DNA

Date & Time
9 June 2005 (Thu), 1:30 pm - 2:30 pm
6F seminar room, Sengen site
Professor Mauro Boero
Institute of Physics, University of Tsukuba(筑波大学物理学系)
Charge localization phenomena in synthetic DNA
Charge transfer in DNA is currently the subject of intense theoretical and experimental investigation. This is due both to a possible use of DNA as a component in nanoelectronic and electrochemical devices and to the fundamental role of conductivity in the oxidative damage and mutations of DNA. By using Car-Parrinello molecular dynamics, we study the mechanism of positive charge and electron hole localization in a laboratory realizable radical cation Z-DNA crystal[1]. We find that at room temperature structural deformation are not sufficient to provide an efficient localization mechanism. Instead we find evidence for both an ion-gated and proton-coupled mechanism[2]. Namely, a hole h+ can be localized by two mechanisms: (i) proton shift or (ii) fluctuations in the solvation shell[3] (with some warning). Between these two scenarios, the proton-coupled charge transfer mechanism seems to provide the best agreement and the key to interpret EPR and H/D substitution experiments. Due to the large size of the full quantum system, this calculation was performed on the Earth Simulator (ES) computer facility[4]. Work is now in progress on a hybrid QMMM system, coupled to metadynamics, to work out charge localization reaction paths and related activation barriers: few details will be given as closing remarks.
Dr. Hiori Kino (木野日織)