Vol. 15, issue 12, article # 1

Bykov A. D., Voronin B. A., Voronina S. S. Estimates of rotational constants for (0V20) vibrational states of the H2O molecule. // Atmospheric and oceanic optics. 2002. V. 15. No. 12. P. 953-957. PDF
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Rotational A, B, C, and centrifugal distortion constants for high-excited bending (0V0)-type states of the H2O molecule were derived from ab initio calculations of Partridge and Schwenke. Energy levels with J = 0, 1, and 2, for V2 = 0 ... 17, which are eigenvalues of the 1x1 effective Hamiltonian matrix, were used. Fitting was performed by the least square method; all states were considered as isolated. The rms error did not exceed 0.3 cm-1 for all cases except for the (0 11 0) state. The standard deviation for this case was more than 1 cm-1 that may be explained by the influence of resonance interactions. The exponential equation used earlier reproduced our data satisfactorily for the lower values of V2. The growth of the A and centrifugal distortion constants with increasing V2 does not occur. Above the barrier to linearity, the parameter A becomes stable at the level of 1000 cm-1 and the centrifugal distortion constant - at the level of 200 cm-1. This can be explained by the effect of strong centrifugal distortion forces at high values of V2. For the B and C rotational constants, the strong vibrational dependence was not observed.