Localization phenomena in a DNA double helix structure : A twisted ladder model

摘要

In this work we propose a model for DNA double helix within the tight-bindingframework that incorporates the helicity of the molecules. We have studiedlocalization properties of three DNAsequences,the periodic poly(dG)-poly(dC)and poly(dA)-poly(dT) sequences and the random ATGCsequence, all of which arecoupled to backbone withrandom site energies representing theenvironmentalfluctuations. We observe that due to helicity of DNA, electrontransport is greatly enhancedand there exists almost a disorder-strengthindependent critical value of the hopping integral, thataccounts for helicityof DNA, for which the electronic states become maximally extended. We havealsoinvestigated the effect of backbone energetics on the transmission and I-Vcharacteristics of DNA.