THERM: a computer code for estimating thermodynamic properties for species important to combustion and reaction modeling.

A computer package has been developed called THERM, an acronym for THermodynamic property Estimation for Radicals and Molecules. THERM is a versatile computer code designed to automate the estimation of ideal gas phase thermodynamic properties for radicals and molecules important to combustion and reaction-modeling studies. Thermodynamic properties calculated include heat of formation and entropies at 298 K and heat capacities from 300 to 1500 K. Heat capacity estimates are then extrapolated to above 5000 K, and NASA format polynomial thermodynamic property representations valid from 298 to 5000 K are generated. This code is written in Microsoft Fortran version 5.0 for use on machines running under MSDOS. THERM uses group additivity principles of Benson and current best values for bond strengths, changes in entropy, and loss of vibrational degrees of freedom to estimate properties for radical species from parent molecules. This ensemble of computer programs can be used to input literature data, estimate data when not available, and review, update, and revise entries to reflect improvements and modifications to the group contribution and bond dissociation databases. All input and output files are ASCII so that they can be easily edited, updated, or expanded. In addition, heats of reaction, entropy changes, Gibbs free-energy changes, and equilibrium constants can be calculated as functions of temperature from a NASA format polynomial database.