Title screen

A theory of the transformed dipole moment operator for nonrigid H2X-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 ℮. 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 µex(℮), µ1x(℮) and µ3z(℮) from the expansion of the molecular fixed component µa(℮, q) (a = x, y, z) of the electric dipole moment of the H2O molecule over q normal coordinates. Some different model forms for this function have been used.