Effects of electrode contact on geometry structure and transport properties of the graphene-based nanomolecule Devices

A series of graphene-based nanomolecule devices are constructed by connecting the graphene nanodot to two Au electrodes through different bond length between the electrodes and molecules. The geometric structure and electronic properties are studied by using density functional theory calculations. Basing on the optimized structure, we calculate the quantum conductance of the system by using the Green´s function method. We find that the geometry structures of the molecule and the transport properties are sensitive to the bond length d_Au-H. The plane of carbon atoms increasingly bends with the decrease of the d_Au-H. The I_SD-VSD curves have the same threshold value under different d_Au-H.