Spherical Transition Moment
This transition moment must be used for multiphoton or
Raman transitions.
It is also appropriate for single photon transitions
classified as parallel or perpendicular, as noted below. For
linear
molecules the "Strength" number is the value of the vibronic only
matrix element:
T(k,q) = <stateA, Λ+q| μ | stateB, Λ>
where k is the "Rank" and
q the "Component" setting,
normally
chosen to be >= 0. The corresponding matrix element:
T(k,-q) = <stateA, Λ-q| μ | stateB, Λ>
is then computed by symmetry. The
order of the states (which can be significant in cases involving
multiple transition moments) is as displayed in the constants
window.
Strictly all the above matrix elements should have selection rules
ΔS
= 0 (and ΔΣ = 0 for linear molecules), but as an extension
PGOPHER relaxes this
requirement for ΔS ≠ 0 transitions and only enforces the
|ΔΩ| =
q rule. See the
section on
Forbidden Transitions in Linear
Molecules for a more detailed discussion of
this.
Settings
| Rank |
Rank of transition: 1 for a normal electric dipole
transition; see here for
multiphoton or Raman
transitions |
| Component |
Projection quantum number of transition moment. The
default
is auto, which
for simple
cases implies taking the only value of the component which
gives an
allowed transitions. In the standard one photon case it will
be 0 for a
parallel transition and 1 for a perpendicular transition.
For more
complicated cases auto
will not work and a specific component must be taken.
|
Parameters
| Strength |
Transition (dipole)
moment. For one photon transitions this has units of Debye.
Note that
the relative intensity is proportional to the square of this
value. |
Molecule Types Linear Molecules Transition Moments