We report on an efficient self‐consistent technique for quantum transport of nanostructures bridged between two metallic electrodes. The method is based on the density‐functional theory using the recursion‐transfer‐matrix (RTM) method with a separable form of norm‐conserving nonlocal pseudopotentials. With this method, we have performed calculations of the conductance through Al atomic‐wires with various kinds of a single atom mixed at the contact to one electrode. We found that the bonding nature of the atom at the contact affects the transport properties significantly. © 2003 American Institute of Physics