A parameter set describing the Ge-H bonds in the framework of the many-body interatomic potential proposed by Tersoff and Murty has been derived using first-principles calculations. The potential was fitted to reproduce structural, energetic, and vibration properties of gas phase germanium hydrides and radicals. It demonstrates a good transferability for the description of hydrogen terminated germanium surfaces. The potential has been used to simulate the epitaxial growth of a Si layer on a Ge(100) surface using SiH4 precursor molecules. The obtained results faithfully reproduce the impact of chemisorbed hydrogen on the mechanism of Ge diffusion in the grown Si layer.