noHFS=True, # there seems to be a problem where HFS
# for K >= 6 is included *incorrectly*
show_upper_degeneracy=True)
freqs = np.array(slaim['Freq-GHz']) * u.GHz
aij = slaim['Log<sub>10</sub> (A<sub>ij</sub>)']
deg = slaim['Upper State Degeneracy']
EU = (np.array(slaim['E_U (K)']) * u.K * constants.k_B).to(u.erg).value
ref_freq = 217.10498 * u.GHz
vdiff = (np.array(-(freqs - ref_freq) / ref_freq) * constants.c).to(u.km /
u.s).value
nl = nodes.Nodelist()
nl.findnode('cdms')
cdms = nl.findnode('cdms')
request = r.Request(node=cdms)
# Retrieve all species from CDMS
result = request.getspecies()
molecules = result.data['Molecules']
sio = [
x for x in molecules.values() if (x.StoichiometricFormula) == ('OSi') and (
x.OrdinaryStructuralFormula == 'SiO')
][0]
sio_inchikey = sio.InChIKey
# query everything for sio
query_string = "SELECT ALL WHERE VAMDCSpeciesID='%s'" % sio.VAMDCSpeciesID
request.setquery(query_string)
def get_molecular_parameters(molecule_name,
molecule_name_vamdc=None,
tex=50,
fmin=1 * u.GHz,
fmax=1 * u.THz,
line_lists=['SLAIM'],
chem_re_flags=0,
**kwargs):
"""
Get the molecular parameters for a molecule from the CDMS database using
vamdclib
Parameters
----------
molecule_name : string
The string name of the molecule (normal name, like CH3OH or CH3CH2OH)
molecule_name_vamdc : string or None
If specified, gives this name to vamdc instead of the normal name.
Needed for some molecules, like CH3CH2OH -> C2H5OH.
tex : float
Optional excitation temperature (basically checks if the partition
function calculator works)
fmin : quantity with frequency units
fmax : quantity with frequency units
The minimum and maximum frequency to search over
line_lists : list
A list of Splatalogue line list catalogs to search. Valid options
include SLAIM, CDMS, JPL. Only a single catalog should be used to
avoid repetition of transitions and species
chem_re_flags : int
An integer flag to be passed to splatalogue's chemical name matching
tool
Examples
--------
>>> freqs, aij, deg, EU, partfunc = get_molecular_parameters(molecule_name='CH2CHCN',
... fmin=220*u.GHz,
... fmax=222*u.GHz,
... molecule_name_vamdc='C2H3CN')
>>> freqs, aij, deg, EU, partfunc = get_molecular_parameters('CH3OH',
... fmin=90*u.GHz,
... fmax=100*u.GHz)
"""
from astroquery.vamdc import load_species_table
from astroquery.splatalogue import Splatalogue
from vamdclib import nodes
from vamdclib import request
from vamdclib import specmodel
lut = load_species_table.species_lookuptable()
species_id_dict = lut.find(molecule_name_vamdc or molecule_name,
flags=chem_re_flags)
if len(species_id_dict) == 1:
species_id = list(species_id_dict.values())[0]
elif len(species_id_dict) == 0:
raise ValueError("No matches for {0}".format(molecule_name))
else:
raise ValueError(
"Too many species matched: {0}".format(species_id_dict))
# do this here, before trying to compute the partition function, because
# this query could fail
tbl = Splatalogue.query_lines(fmin,
fmax,
chemical_name=molecule_name,
line_lists=line_lists,
show_upper_degeneracy=True,
**kwargs)
nl = nodes.Nodelist()
nl.findnode('cdms')
cdms = nl.findnode('cdms')
request = request.Request(node=cdms)
query_string = "SELECT ALL WHERE VAMDCSpeciesID='%s'" % species_id
request.setquery(query_string)
result = request.dorequest()
Q = list(
specmodel.calculate_partitionfunction(result.data['States'],
temperature=tex).values())[0]
def partfunc(tem):
Q = list(
specmodel.calculate_partitionfunction(result.data['States'],
temperature=tem).values())[0]
return Q
freqs = np.array(tbl['Freq-GHz']) * u.GHz
aij = tbl['Log<sub>10</sub> (A<sub>ij</sub>)']
deg = tbl['Upper State Degeneracy']
EU = (np.array(tbl['E_U (K)']) * u.K * constants.k_B).to(u.erg).value
return freqs, aij, deg, EU, partfunc