▎ 摘　　要

In the present paper, a new method is proposed to distinguish the DNA nucleotides based on a first-principles calculation of the electronic features of DNA bases which are chemisorbed to a graphene sheet placed between two gold electrodes in a contact-channel-contact system. The capacitance properties of graphene in the channel are simulated and analyzed using non-equilibrium Green's functions combined with density functional theory. Thus, the capacitance properties of graphene are theoretically deciphered in a biological environment, and, using a novel method, the effect of the chemisorbed DNA nucleotides on electrical charges on the surface of graphene is investigated. Several parameters in this method are also extracted including the electrostatic energy, induced density, induced electrostatic potential, electron difference potential, and electron difference density. The qualitative and quantitative differences among these parameters can be used to identify DNA nucleotides.