VVW Flag

RFM Flags: Apply Van Vleck-Weisskopf Correction to Lineshape

04DEC23

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
  1. 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).
  2. 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.

Bugs
[none recently]