Effective dipole-moment operator for nonrigid H2X-type molecules. Application to H2O

Abstract A theory of the transformed dipole moment operator for nonrigid H 2 X-type molecules has been worked out using the method of contact transformation. The treatment takes into account the large amplitude bending motion, which is described by the coordinate ϱ. Formulae obtained for the transformed dipole moment operator for bending vibration quantum bands and for combination bands have been used for the determination of the functions μ e x (ϱ), μ 1 x (ϱ) and μ 3 z (ϱ) from the expansion of the molecular fixed component μ α (ϱ, q ) (α = x , y , z ) of the electric dipole moment of the H 2 O molecule over q normal coordinates. Some different model forms for this function have been used.