converting values from NIST Webbook to TDLIB
Evgenii Rudnyi
I have made a Python script to convert the values from the NIST Webbook to
TDLIB. A few notes.
I have used a standard element reference (SER) introduced by SGTE (see for
example A.T. Dinsdale. SGTE data for pure substances. CALPHAD, 1991, v.
15, N 4, p. 317-425.) to represent the Gibbs energy. That is, the Gibbs
energy is relative to enthalpies of elements in the standart state at
298.15
G_SER = G - Sum_i H_i(298.15)
It means that in this respresentation
G_SER = Del_f_H(298.15) + H - H_298.15 - T S
and it has an absolute value. You should remember that we cannot determine
the absolute value of the Gibbs energy by itself.
I am not sure I understand how the coefficients F, G, H have been computed
at the NIST Webbook and as a result I have not used them. I have used only
the coefficients for the heat capacity. Then we need additionally two
constants, that have been determined by using the enthalpy of formation
and the entropy at 298.15 from another table.
The procudure is as follows. One makes a datafile. The first line is the
name, the second is the enthalpy of formation at 2981.5, and the third is
the entropy at 298.15. Then go the coefficients from the table - it is
possible just to copy and paste them from the Web. See data.txt as an
example for the input file.
Then the script reads this file and writes an output file in the format
that TDLIB understands. The thermodynamics properties, produced in TDLIB
are consistent with those in the NIST Webbook.
Try it. If you have questions, please ask.
Best wishes,
Evgenii