Eur. Phys. J. E (2005) 17: 149-154
https://doi.org/10.1140/epje/i2004-10135-8

Regular Articles

Localization properties of electronic states in a polaron model of poly(dG)-poly(dC) and poly(dA)-poly(dT) DNA polymers

¹ Aoyama 5-7-14-205, 950-2002, Niigata, Japan
² Center for Structural Biochemistry NOVUM, Karolinska Institute, S-14157, Huddinge, Sweden
³ Institut für Theoretische Physik, Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195, Berlin, Germany
⁴ Grupo de Fısica No Lineal (GFNL), Departamento de Fısica Aplicada I, ETSI Informática, Universidad de Sevilla, Avda Reina Mercedes s/n, 41012, Sevilla, Spain

^* e-mail: hyamada@uranus.dti.ne.jp
^** e-mail: starikow@chemie.fu-berlin.de
^*** e-mail: hennigd@physik.fu-berlin.de
^**** e-mail: archilla@us.es

Received: 7 September 2004
Accepted: 23 March 2005
Published online: 20 May 2005

Abstract

We numerically investigate localization properties of electronic states in a static model of poly(dG)-poly(dC) and poly(dA)-poly(dT) DNA polymers with realistic parameters obtained by quantum-chemical calculation. The randomness in the on-site energies caused by the electron-phonon coupling is completely correlated to the off-diagonal parts. In the single electron model, the effect of the hydrogen-bond stretchings, the twist angles between the base pairs and the finite system size effects on the energy dependence of the localization length and on the Lyapunov exponent are given. The localization length is reduced by the influence of the fluctuations in the hydrogen bond stretchings. It is also shown that the helical twist angle affects the localization length in the poly(dG)-poly(dC) DNA polymer more strongly than in the poly(dA)-poly(dT) one. Furthermore, we show resonance structures in the energy dependence of the localization length when the system size is relatively small.