All the harmonic, the diagonal cubic and quartic stretching and the semidiagonal cubic force constants of HCP have been calculated from Hartree-Fock wavefunctions by the force method of Pulay. The force constants are in good agreement with the experimental ones, except for FRR, Faa, FRr, FRaa, and Fraa the latter two being rather uncertain from experiment. From the harmonic force constants, harmonic frequencies have been calculated by the method of Wilson and Eliashevich. The equilibrium geometry of HCP has been calculated by the force relaxation method of Pulay.