Molecule Types Vibrational Structure <Prev Next>

Vibrational Perturbation

Add one one these items for every extra term required in the Hamiltonian.

Settings

Nucleus Not used
SymSelect Symmetry select
ScalePrev Scale factor with respect to preceding perturbation
Op Type of perturbation: x, q, qSigned, Gaussian. See below for details
EffectiveQno Set to group together states connected by this perturbation when assigning quantum numbers.
v1
 One entry per mode; power of each mode (ni) in the overall perturbation operator
v2
...

Parameters

Value Size of perturbation.
Exponent Exponent for Gaussian type perturbation

Perturbation Types

In the formulae below, di is the degeneracy of mode i and ni is the vi setting, as above.

x
 Simple diagonal matrix elements with value:
(v1+d1/2)n1(v2+d2/2)n2...
For example to add a conventional x12 term set Op = x, v1 = 1, v2 = 1. 
q
 Product of normal mode operators:
q1n1q2n2...
n1, n2 should all be >= 0
qSigned Product of normal mode operators:
q1n1q2n2...
with the additional selection rule that:
Δv1 = n1, Δv2 = n2, ...
or
Δv1 = -n1, Δv2 = -n2, ...
In this case the signs of n1, n2... are important.
Gaussian Matrix element of exp(-bqi2) where b is the Exponent parameter above for the mode with non zero ni. More than one ni can be set non-zero, though this is probably not useful.