TUNNELING SPLITTINGS IN MODEL 2D POTENTIALS .3. V(X,Y)=LAMBDA(X(2)-X(0)(2))-CXY+1 2KY(2)+(C-2/2K)X(2)/

Vibrational tunneling spectra for a 'linear' potential are calculated with the WKB trajectory method for a wide range of coupling strengths between coordinates, and compared to the quantum mechanical computatio ns. Reasonable agreement is found between the WKB and quantum results, both in the tunneling splittings and wave functions at the 'path-gene rated' dividing line. The method is generalized to N-dimensional symme tric potentials with two equivalent minima. The results are exemplifie d by calculating the vibrational tunneling spectrum in a 3D 'squeezed' potential. The inhomogeneous broadening of tunneling doublets in supe rsonic beams is discussed. In rotationally excited states, the couplin g strength depends on the rotational quantum number, because of the vi bration-rotation interaction. The resultant line width is formed by an ensemble of coherently tunneling systems with a distribution of coupl ing strengths determined by the finite rotational temperature.