DENSITY-FUNCTIONAL AND POST-HARTREE-FOCK EQUILIBRIUM GEOMETRIES, POTENTIAL-ENERGY SURFACE AND VIBRATIONAL FREQUENCIES FOR METHYLAMINE

The equilibrium structure, the potential energy surface and the infrar ed harmonic frequencies are determined by using two generalized gradie nt approximation density functional methods for methylamine. The resul ts are compared to those of a second-order Moller-Plesset and coupled cluster calculations. The DFT methods predict correctly the equilibriu m geometry, the inversion energy barrier and the infrared spectra. The B-P86 method show better agreement with the experiment than the MP2 o r CCD methods.