A local anharmonic treatment of vibrations of methane

The stretching and bending vibrations of methane are studied in a local anharmonic model of molecular vibrations. The use of symmetry-adapted operators reduces the eigenvalue problem to block diagonal form. For the 44 observed energies we obtain a fit with a standard deviation of 0.81 cm${}^{-1}$ (and a r.m.s. deviation of 1.16 cm${}^{-1}$).