2-DIMENSIONAL MODEL TREATMENT OF TORSIONAL MOTIONS THE WATER TRIMER

Recently, three far-infrared vibrational excitations were observed for (D2O)(3) in the range 40-100 cm(-1) at very high resolution. These vi brations could be identified with pseudorotations (due to nipping of f ree O-H bonds). However, a one-dimensional model to describe the pseud orotation has thus far failed to conclusively assign the measured band s to pseudorotational transitions. A coupled two-dimensional model tre atment of torsional motions in the water trimer is presented. Based on the computed torsional frequencies and transition moments, new assign ments of the observed vibration-rotation-tunneling spectra are propose d.