Optimized Basis Sets for the Environment in the Domain-Specific Basis Set Approach of the Incremental Scheme

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Domain-specific basis set (DSBS) incremental schemes offer computational efficiency.
• Environmental basis sets are crucial for the accuracy of incremental methods.
• Explicitly correlated (F12) methods improve the treatment of electron correlation.

Purpose of the Study:

• To develop minimal environmental basis sets (DSBSenv) for the DSBS incremental scheme.
• To reduce the computational cost (CPU requirements) of the DSBS incremental scheme.
• To enable the use of DSBSenv with explicitly correlated (F12) methods.

Main Methods:

• Development of minimal basis sets (DSBSenv) based on Ahlrichs' segmented basis sets.
• Optimization of auxiliary basis sets for density fitting and resolution of the identity in F12 calculations.
• Validation of auxiliary sets using small- to medium-sized molecules.
• Testing of reduced DSBSenv basis sets by removing high angular momentum functions.
• Validation of optimized and reduced basis sets on medium- to large-sized systems.

Main Results:

• Density fitting errors are significantly smaller (2-4 orders of magnitude) than basis set incompleteness errors of DSBSenv.
• Optimized DSBSenv basis sets decrease CPU time by 15.4% compared to previous environmental basis sets.
• Reduced DSBSenv basis sets decrease CPU time by 19.4% while retaining accuracy.
• Absolute energy accuracy is maintained with standard deviations of 0.99 and 1.06 kJ/mol for optimized and reduced sets, respectively.

Conclusions:

• The developed DSBSenv minimal basis sets effectively reduce computational cost in DSBS incremental schemes.
• The optimized auxiliary basis sets enable accurate F12 calculations with DSBSenv.
• The optimized and reduced DSBSenv basis sets provide a practical approach to accelerate quantum chemical calculations without significant loss of accuracy.