The stretching, bending, and torsional force-field parameters for modelling Si (111) surfaces functionalized with alkylamines have been derived from energies, optimized geometries and harmonic frequencies obtained by accurate quantum mechanical calculations. Addition of inter-chain non-bonded parameters from a literature force field leads to computed energies in good agreement with their quantum mechanical counterparts for a large set of geometrical arrangements. The overall force-field was tested through molecular dynamics simulations performed on several models of Si functionalized surfaces, with different coverage percentages. Preliminary results indicate that the presence of a polar terminal amine group yields a surface coating of around 50%.