Comment on "New Scaling of Child-Langmuir Law in the Quantum Regime"

In their letter on the quantum Child-Langmuir law, Ang, Kwan and Lau (Phys. Rev. Lett. 91, 208303 (2003)) include exchange correlation effects within the Kohn-Sham density functional theory and explore numerically the maximum transmitted current in nanogaps. We show here that the calculations are in error as the exchange-correlation component of the chemical potential has been ignored while fixing the boundary conditions for the Hartree potential.