The authors report a theoretical analysis of electron transport in a Si atom wire at a finite bias voltage using a first-principles method. Electronic states and transport properties are calculated using the Lippmann-Schwinger equation using the Laue representation in the framework of the density functional theory. They analyzed the transport properties of the Si wires between the metallic electrodes, and elucidated potential drop, transmission spectra, and the dependence on the bias voltage. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3065484]