Before revision: S. Datta, Electronic Transport in Mesoscopic Systems, Cambridge University Press, 1995, Derivation In a 1D wire, connecting two reservoirs of potential and adiabatically: The density of states is where the factor 2 comes from electron spin degeneracy, is the Planck constant, and is the electron velocity.
After revision: Derivation In a 1D wire, connecting two reservoirs of potential and adiabatically: The density of states is where the factor 2 comes from electron spin degeneracy, is the Planck constant, and is the electron velocity.