Computing cross sections (Examples) - Trovemaster/exocross GitHub Wiki

The method is described in: C. Hill, S. N. Yurchenko, J. Tennyson, "Temperature-dependent molecular absorption cross sections for exoplanets and other atmospheres", Icarus, 226, 1673-1677 (2013). link to article

  • Gaussian profile, HWHM is the half-width at half-maximum.

Example:

Temperature  2000.0
Range 0.0  12000.0

Npoints 200001
absorption
Gaussian  
HWHM 0.5 (cm-1)
threshold 1e-40 (to skip weak lines)

output abs_gauss_0.5_T2000.0

States  "../all/ch4-50.states-all"

Transitions
 a-03000.dat
 a-03100.dat
 a-03200.dat
 a-03300.dat
 a-03400.dat
 a-03500.dat
 a-03600.dat
 a-03700.dat
 a-03800.dat
 a-03900.dat
end
  • Doppler profile

Doppler m is the effective mass of the molecule in amu.

Example

Temperature  1500.0
Range 0.0  12000.0
Npoints 200001

emission
doppl
mass 16.0313

output dop_emiss_1500.0
States ch4-50.states-all

Transitions a-02100.dat
  • Lorentzian profile

Lorentz

where b is the normalization factor.

Example:

Temperature  300
Range 0.0  10000.0
Npoints 10001

absorption
Loren  
HWHM 0.1 (cm-1)

output abs_lor_0.1_T300.0

States  NaH.states

Transitions NiH.trans
  • Stick spectrum

Example

(ScH stick spectrum)
Temperature 1500.0
Range 0.  16000.0

Npoints 16001

absorption
stick 
threshold 1e-29

output ScH_1500K_stick
States       ScH.states
Transitions  ScH.trans
  • bin give average intensity per the wavenumber or wavelength interval as defined by Range/(Npoints-1). The wavelength is invoked by adding um to the range values

Example:

(ScH bin spectrum)
Temperature 1500.0
Range 0.  16000.0

Npoints 16001

absorption
bin  

output ScH_1500K_bin_stick
States       ScH.states
Transitions  ScH.trans

or

(ScH bin spectrum)
Temperature 1500.0
Range 1.  100.0 um (or micron)
  • Box gives the maximal transition intensity per wavenumber interval, which is a cheaper alternative for the stick spectrum

Example:

(ScH box spectrum)
Temperature 1500.0
Range 0.  16000.0

Npoints 16001

abundance 0.97

absorption
box
threshold 1e-29

output ScH_1500K_box_stick
States       ScH.states
Transitions  ScH.trans

The intensity cut-off (stick) can be done using the HITRAN method: S = S0 nu/nu0 tanh(c2 nu /2/T) for nu<=2000 cm-1 and 1e-29 cm/molecule above.

absorption
stick
cutoff HITRAN (S_crit) 1e-29  nu_crit 2000 

output ScH_1500K_box_stick
States       ScH.states
Transitions  ScH.trans