Deciphering the electric field changes in the channel of an open quantum system to detect DNA nucleobases

Abstract

DNA nucleobases strongly absorbed onto a graphene sheet placed between two gold electrodes in a contact---channel---contact configuration were distinguished. We analyzed the system using the nonequilibrium Green's function method combined with density functional theory. The changes of the electric field in the middle of the vacuum gap (channel) were investigated. The Mulliken population was deciphered for graphene and the nucleobases. We also extracted the image plane, which was found to lie very close to the position of peak induced density. The projection of the electron difference density and electrostatic difference potential of the nucleobases are also presented. The nucleobases were rotated around the z-axis from $$0^\circ $$0ź to $$180^\circ $$180ź in steps of $$20^\circ $$20ź, and the isosurfaces for the electron difference density and electron difference potential plotted. The qualitative and quantitative differences among these parameters were used as criteria to identify the DNA nucleobases.