The two probe is described in
Mads Brandbyge, José-Luis Mozos, Pablo Ordejón, Jeremy Taylor, and Kurt Stokbro, Density-functional method for nonequilibrium electron transport, Physical Review B 65, 165401 (2002). Abstract
The electrostatic regions is described in:
* K. Stokbro, D. E. Petersen, S. Smidstrup, A. Blom, M. Ipsen and K. Kaasbjerg, Phys. Rev. B 82, 075420 (2010)
for a longer review you may check
1.K. Stokbro, J. Taylor, M. Brandbyge and H. Guo, Ab-initio based non-equilibrium Green's function formalism for calculating electron transport in molecular devices, Chapter in Introducing Molecular Electronics, Lecture Notes in Physics, Vol. 680 (Springer, Berlin, Dec. 2005), Editors G. Cuniberti, G. Fagas and K. Richter.
