MP2/CBS atomic and molecular benchmarks for H through Ar.

Area of Science:

• Quantum Chemistry
• Computational Chemistry
• Theoretical Chemistry

Background:

• Accurate calculation of electron correlation is crucial for understanding chemical phenomena.
• Previous methods often involved approximations that limited accuracy or increased computational cost.
• Developing reliable benchmarks is essential for validating new computational approaches.

Purpose of the Study:

• To compute highly accurate second-order correlation energies for a comprehensive set of 72 atomic and molecular species.
• To establish benchmark values at the MP2/Complete Basis Set (CBS) limit.
• To provide reference data for calibrating approximate quantum chemical calculations.

Main Methods:

• Extrapolation to the Complete Basis Set (CBS) limit using a series of augmented polarized basis sets (n-tuple-zeta, n=4-7).
• Application of the second-order Møller-Plesset perturbation theory (MP2) method.
• Calculation of correlation energies for atoms, ions, homonuclear diatomics, and hydrides from the first two rows of the Periodic Table.

Main Results:

• Achieved highly accurate MP2/CBS limits for 72 distinct chemical species.
• Demonstrated agreement within +/-0.1% with accurate numerical reference values for selected atoms and ions.
• The calculated correlation energies provide a reliable dataset for benchmark purposes.

Conclusions:

• The computed MP2/CBS limits serve as valuable benchmarks for evaluating approximate quantum chemical methods.
• This work provides a foundation for developing more efficient and accurate computational chemistry tools.
• The established benchmarks facilitate the advancement of theoretical chemistry and materials science.