To allow for a variation in the vibronic
transition dipole moment with rotational state, commonly described
in terms of Herman-Wallis factors, an arbitrary function can be
associated with any
Transition
Moment object. To do this, create a
Custom Transition
Function under the transition moment of interest (right
click on the transition moment, select "Add New" and then "Custom
Transition Function") and enter the required expression in the "
Comment"
field of the object. To enter a typical form for a parallel band
in a linear molecule (see Watson 1987) use: