The RTM/NEGF Method for ab initio Calculations of Electron Transport through Nano-Structures

We develop a first-principles calculation method for the quantum transport through nanostructures between electrodes by using the recursion-transfer-matrix (RTM) method combined with the nonequilibrium Green function (NEGF) method. This RTM/NEGF method is applied to the electronic states and current-voltage (I-V) characteristics of atomic-scale nanocontact system. We observe a non-linear behavior in the I-V characteristics and correspondingly a gap structure appears in the differential conductance. We find that such a non-linear behavior emerges when the transport properties change from tunneling to ballistic regimes.