Database of small molecule thermochemistry for combustion

Area of Science:

• Computational Chemistry
• Chemical Thermodynamics
• Combustion Science

Background:

• Accurate thermochemical data is essential for developing reliable combustion kinetic models.
• Existing databases may contain discrepancies and errors, impacting model accuracy.
• Radical, biradical, and triplet species are particularly important but challenging to characterize.

Purpose of the Study:

• To compute high-accuracy ab initio thermochemistry for 219 small molecules relevant to combustion.
• To develop a bond additivity correction to enhance enthalpy calculations.
• To provide the most accurate and comprehensive thermochemical data available for these species.

Main Methods:

• Utilized the RQCISD(T)/cc-PV∞QZ//B3LYP/6-311++G(d,p) method for electronic energy computations.
• Developed a bond additivity correction using Active Thermochemical Tables for enthalpy refinement.
• Performed uncertainty analysis for entropy and heat capacity.

Main Results:

• Achieved standard-state heat of formation with 3σ uncertainty of 0.9 kcal/mol, meeting chemical accuracy.
• Presented comprehensive thermochemical data, often superior to existing values.
• Identified and helped resolve significant discrepancies with published databases.

Conclusions:

• The generated thermochemical data is highly accurate and reliable for combustion chemistry.
• This work provides a valuable resource, improving upon and correcting existing datasets.
• The findings are critical for advancing accurate kinetic modeling in combustion research.