Embedded Green-function approach to the ballistic electron transport through an interface

We present an efficient method for calculating the conductance of ballistic electrons through an interface from first principles using the embedding approach of Inglesfield. In our method the Landauer-B\"uttiker formula for ballistic transport is expressed in terms of two quantities that are available in the embedded Green-function formalism without additional calculations. One is the embedding potential of bulk crystals on both sides of the interface and the other is the Green function in the interface region. As a proof of principle we calculate on the basis of the density-functional theory the spin-resolved electron transmission through a model system of ferromagnetic Co monolayers sandwiched between bulk Cu crystals. The relationship between our formulation and the Green-function formulation of Baranger and Stone is discussed.