Efficient Estimation of Formation Enthalpies for Closed-Shell Organic Compounds with Local Coupled-Cluster Methods

Area of Science:

• Computational chemistry
• Thermochemistry

Background:

• Accurate determination of enthalpies of formation is crucial for understanding chemical reactions and properties.
• Existing computational methods often require significant resources or lack experimental accuracy.

Purpose of the Study:

• To investigate efficient computational schemes for estimating enthalpies of formation of closed-shell organic compounds.
• To assess the accuracy and uncertainty of local coupled-cluster with single, double, and perturbative triple excitation (CCSD(T)) approximations.

Main Methods:

• Utilized atom-equivalent-type computational schemes.
• Employed various local coupled-cluster approximations, including CCSD(T).
• Analyzed sources of uncertainty, such as frozen-core contributions and zero-point energy anharmonicity.

Main Results:

• The proposed estimation framework has a lower limit of expanded uncertainty of approximately 2 kJ·mol⁻¹.
• The best-performing computational schemes achieved an expanded uncertainty of about 2.5 kJ·mol⁻¹ when validated against 44 experimental values.
• Demonstrated computational efficiency and accuracy comparable to experimental measurements.

Conclusions:

• The developed computational methodology offers significant advantages for practical applications in chemistry.
• Enables prompt validation of experimental measurements, estimation of missing data, and resolution of conflicting experimental results.
• The approach eliminates the need for auxiliary reactions and additional experimental data, streamlining the process.