Localization Properties of Electronic States in Polaron Model of poly(dG)-poly(dC) and poly(dA)-poly(dT) DNA polymers

摘要

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