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Center for Nonlinear Studies |
The internal electronic structure of single DNA base molecules, i. e. guanine, adenine, cytosine, and thymine, adsorbed on a metallic surface of Cu(111), is determined in detail using density functional theory computations. In contrast to the intuitive belief, that electronic structure of a molecule is only slightly disturbed in a weakly interacting substrate, our simulations reveal strong hybridizations and interactions between molecular and metallic states. The calculated local electron densities of state spectra demonstrate the absence of pure localized molecular states for all four DNA bases, providing guidelines for interpreting DNA conductance spectra in the STM measurements. These results open new prospective for understanding of bio-molecule adsorbate and have an important implication for a possible differentiation of nucleotide sequences in DNA through STM.