Geometric phase effects in the vibrational spectrum of Na-3(X)

The lowest 89 vibrational energy levels for Na-3(X) for zero total angular momentum (J = 0) are computed both with and without the geometric phase. The calculations are full dimensional (3D) and utilize the vector potential (gauge theory) approach for including geometric phase effects. Tt is shown that the geometric phase leads to large shifts in the vibrational energy levels which result in a different ordering of states. These results can be verified experimentally and represent the first ''clean'' example of a geometric phase effect in molecular spectra.