Electron-transport properties of Na nanowires under applied bias voltages

We present first-principles calculations on electron transport through Na nanowires at finite bias voltages. A nanowire exhibits a nonlinear current-voltage characteristic and negative differential conductance (NDC). NDC is induced by the drastic suppression of the electron-transmission peaks which is attributed to the reduction of the electron conductance through the negatively biased side of the system. The mechanism of the occurrence of NDC is also demonstrated based on the finding that a voltage drop locally occurs on the negatively biased end of the nanowire.