Conductance calculations with a wavelet basis set

We present a method based on density functional theory (DFT) for calculating the conductance of a phase-coherent system. The metallic contacts and the central region where the electron scattering occurs, are treated on the same footing taking their full atomic and electronic structure into account. The linear-response conductance is calculated from the Green’s function which is represented in terms of a system-independent basis set containing wavelets with compact support. This allows us to rigorously separate the central region from the contacts and to test for convergence in a systematic way. The method supports the use of both norm-conserving and ultrasoft pseudopotentials. We use the method to study the effect of adsorbates on the conductance of an infinitely long, atomically thin Al wire, and find that hydrogen and oxygen effectively reduce the conductance of the wire by one and two conductance quanta, respectively.