ExoCross can use the precomputed _binned_ cross-sections (i.e. with keyword bin) in order to put a line-profile on such a _binned_ transition treating it as a single line with a combined intensity. It is therefore assumed that the corresponding binned-cross-sections are pre-computed for a given T. The advantage of this approach is that calculations of the cross-sections for line-profiles are much faster due to the smaller number of bins relative to the number of lines.
The approximation used is that the line-centres for all transitions within a given bin sifted to the centre of the bin.
This option can be invoked by giving a keyword histogram (or histogram-J, see below) anywhere in the body of the inout file. The states file in this case is used only for the partition function. The histograms (binned-cross-sections) are then given as usual transition files. Otherwise the input file is as usual.
Temperature 296.0 Range 0.0 10000.0 Npoints 10001 absorption gauss hwhm 0.5 (cm-1) histrogram output C2H2_ab_g0.5 States H2O.states Transitions H2O_T1000K_bin.xsec
In order to be able using J-dependent Voigt line-profiles, a J-value can be given together with the transition filename. In this case the histrogramJ keyword has to be used instead of histogram.
histogram-J Temperature 1000.0 pressure 1 Range 0.0 10000.0 Npoints 1000001 species. He gamma 0.0043 n 0.02 t0 298.0 file 1H2-16O__Nina__He__a1.broad model JJ ratio 0.16 H2 gamma 0.0207 n 0.027 t0 298.0 file 1H2-16O__Nina__H2__a1.broad model JJ ratio 0.84 end absorption voi-quad mass 18 output H2O_voi-q_1000K_1bar offset 25.0 nquad 40 States 1H2-16O__BT2.states Transitions bin-J0_T3500_grid1_1e-4.xsec 0 bin-J1_T3500_grid1_1e-4.xsec 1 bin-J2_T3500_grid1_1e-4.xsec 2 bin-J3_T3500_grid1_1e-4.xsec 3 bin-J4_T3500_grid1_1e-4.xsec 4 bin-J5_T3500_grid1_1e-4.xsec 5 end
A histogram can be produced using BIN as the “line-profile” type. This can be combined with the wavelength-range used instead of wavenumber-range (default) by providing um or micron as units in RANGE. `Bin’ is used to bin all intensities into different wavenumber/wavelength grid points.
Temperature 296.0 Range 1.0 1000.0 um Npoints 10001 absorption bin