Specific heatsΒΆ
Please provide the line lists, temperature step Ntemp and the
maximum of the temperature Tmax.
Ntemp is always set as 1 K.
Tmax can be set by yourself and the definition file .def from
the ExoMol database provides the maximum temperature of each molecule
for reference.
The temperatures are start from 1 K to Tmax K in the output file.
The specific heats equation is:
\[
C_p(T) = R\left [\frac{Q''}{Q}-\left (\frac{Q'}{Q} \right )^2 \right ]+\frac{5R}{2},
\]
where the partition function :math:Q(T) and its first two moments are:
\[
Q(T)=\sum_n g_n^{\textrm{tot}}e^{-c_2\tilde{E}_n/T},
\]
\[
Q'(T) = T\frac{\mathrm{d} Q}{\mathrm{d} T} =\sum_n
g_n^{\textrm{tot}}\left(\frac{c_2 \tilde{E}_n}{T}\right)\exp\left(-\frac{c_2 \tilde{E}_n}{T}\right),
\]
\[
Q''(T) = T^2\frac{\mathrm{d}^2 Q}{\mathrm{d} T^2}+2Q' =\sum_n g_n^{\textrm{tot}}
\left(\frac{c_2 \tilde{E}_n}{T}\right)^2\exp\left(\frac{c_2 \tilde{E}_n}{T}\right).
\]
Example
# Data source #
Database ExoMol
Molecule CO2
Isotopologue 12C-16O2
Dataset UCL-4000
SpeciesID 21
# File path #
ReadPath /mnt/data/exomol/exomol3_data/
SavePath /home/jingxin/data/pyexocross/
LogFilePath /home/jingxin/data/pyexocross/log/CO2_ExoMol_cp.log
# Functions #
Conversion 0
PartitionFunctions 0
SpecificHeats 1
CoolingFunctions 0
Lifetimes 0
OscillatorStrengths 0
StickSpectra 0
CrossSections 0
# Cores and chunks #
NCPUtrans 4
NCPUfiles 4
ChunkSize 1000000
# Calculate partition, specific heats or cooling functions #
Ntemp 1 # The number of temperature steps
Tmax 5000 # Maximal temperature in K
Note
If the line lists data is not in the ExoMol format, please convert your
data format into the ExoMol format at first and then compute specific
heats with PyExoCross.
So please read Conversion and write 1 after Conversion, 2 after ConversionFormat and fill Conversion section.