Knowledge Bank

The origin of the Coriolis constant (zeta), associated with degenerate normal modes of vibration of some $XY3Z$ type molecules has been examined. There are known regularities in the magnitude and the signs of zetas for a series of molecules of related structure, e.g. for $CH3X$ molecules approximate zetas are: $\zeta (stretch)=0,\zeta (def.)=-0.30$ and $\zeta (rock)=+0.30$. Effects on individual zeta values of variously modified force fields were investigated by examining the influence of the off-diagonal terms in the F matrix. Finally, a sufficiently realistic force field was selected and the mass dependence of the zetas was examined.