We present a comprehensive theoretical study of work functions and surface energies of PtSi and a calculation of the Schottky-barrier height at the Si(001) PtSi(001) interface within the framework of the density functional theory. The p -type Schottky-barrier height of 0.28 eV is found in good agreements with predictions of a simple metal-induced gap states theory and available experiments. This low barrier suggests PtSi as a low contact resistance junction metal for complimentary metal-oxide-semiconductor technology. We correlate the work function with the PtSi surface orientation and estimate surface energies of different surfaces. The low energy terminations correspond well to grain orientations reported for thin PtSi films. © 2006 The American Physical Society.