A larger basis set describes atomization energy core-valence correction better than a higher-order coupled-cluster...

Area of Science:

• Computational Quantum Chemistry
• Theoretical Chemistry
• Physical Chemistry

Background:

• Accurate computation of atomization energies is crucial in theoretical chemistry.
• Core-valence corrections are essential for high-precision calculations.
• Coupled-cluster methods are widely used but require careful parameterization.

Purpose of the Study:

• To assess the accuracy of coupled-cluster (CC) methods for core-valence (CV) corrections to atomization energies.
• To evaluate the impact of basis set size and CC truncation levels on CV correction accuracy.
• To investigate different extrapolation techniques for improving computational results.

Main Methods:

• Employed coupled-cluster methods up to CCSDTQP truncation levels.
• Utilized (aug-)cc-pwCVnZ basis sets (n=D, T, Q, 5).
• Applied canonical, flexible Helgaker, and Riemann zeta function extrapolation techniques.

Main Results:

• Larger basis sets with lower-level CC methods yield more accurate CV corrections, except for CCSD.
• CCSD(T) calculations benefit from larger basis sets, leading to faster computations with modern codes.
• Higher-order or all-electron methods are important for accurate geometry optimizations.

Conclusions:

• Optimizing basis set and CC method combinations is key for accurate CV corrections.
• The findings provide guidance for achieving state-of-the-art accuracy in computational chemistry.
• Understanding these relationships enhances the reliability of theoretical predictions in chemical studies.