Vibrational spectra
===================
.. code-block:: python
    :name: Vibrational spectra
    :linenos:

    import pyarts
    import numpy as np
    
    # initialize ARTS
    ws = pyarts.workspace.Workspace()
    
    # Download ARTS catalogs if they are not already present.
    pyarts.cat.download.retrieve()
    
    # These are the same species as for the rotational spectra (see
    # ../rotational-spectra/start_gui.py) but we also add water, carbon dioxide
    # and methane since these are sometimes more interesting in the infrared.
    # Gone are also the frequency limits, we will later use another speed-up
    # technique to achieve faster copmpute times
    ws.abs_speciesSet(
        species=["HCl",
                 "ClO",
                 "CO",
                 "N2O",
                 "O3",
                 "H2O",
                 "CO2",
                 "CH4"])
    
    # Read the absorption lines.  These should be part of the arts-cata-data package
    ws.abs_lines_per_speciesReadSpeciesSplitCatalog(basename="lines/")
    
    # Speed-up technique of using a cutoff frequency
    # This will apply a cutoff of each absorption line at a frequency of 750 GHz
    # away from the pressure shifted line center.  The value at the cutoff frequency
    # is subsequently used to remove the value from within the line center.
    # the latter modification is in line with how water continua models deal with
    # some of its unknown or just difficult to model absorption features, however
    # we will not consider this absorption in the current example
    # NOTE: Using a cutoff frequency across all species like this degrades the
    # quality of the absorption calculations, which can be seen by changing the
    # Y-scale of the absorption to logarithmic
    ws.abs_lines_per_speciesCutoff(option="ByLine", value=750e9)
    
    # Use an automatic agenda
    ws.propmat_clearsky_agendaAuto()
    
    # Arts setup (No NLTE, no polarization, and standard isotopologue ratios)
    ws.nlte_do = 0
    ws.stokes_dim = 1
    ws.isotopologue_ratiosInitFromBuiltin()
    
    # Settings (Standard atmosphere midlatitude-summer)
    ws.Touch(ws.jacobian_quantities)
    ws.Touch(ws.select_abs_species)
    ws.Touch(ws.rtp_nlte)
    ws.rtp_mag = [10e-6, 20e-6, 40e-6]
    ws.rtp_los = [45, 45]
    ws.rtp_pressure = 110000
    ws.rtp_temperature = 2.942000e+02
    ws.f_grid = pyarts.arts.convert.kaycm2freq(np.linspace(300, 3000, 1000))
    ws.rtp_vmr = [1.000869e-09, 1.000869e-14, 2.850472e-06, 1.501303e-07,
                  3.019448e-08, 1.877431e-02, 3.302947e-04, 1.701397e-06]
    
    # Check that the calculations are OK
    ws.lbl_checkedCalc()
    
    # Start the explorer
    ws.propmat_clearsky_agendaGUI()