RFM Flags: Apply Van Vleck-Weisskopf Correction to Lineshape
14APR24
Enabled
Apply VVW correction term to line-by-line calculations
(unless already calculated using VVW lineshape — see
*SHP
section)
Disabled
Normal lineshapes
Restrictions
None.
Notes
For a line centred at frequency/wavenumber ν0, the
Van Vleck Weisskopf lineshape incorporates the contribution of the
'mirror-reflection' of the line centred at −ν0, so is
generally recommended for
calculations of pressure-broadened lines
in the microwave region (ν <100 cm-1).
The specific Van Vleck Weisskopf lineshape, as specified in the
*SHP section, is a more accurate theoretical
version of the Lorentzian lineshape for this region but if Doppler broadening
is also likely to be significant it is better to apply the VVW correction
to the Voigt lineshape using the VVW Flag than force the full VVW
shape to be used throughout.
