Optimized auxiliary basis sets for explicitly correlated methods

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Explicitly correlated methods like MP2-F12 and CCSD-F12 offer high accuracy in electronic structure calculations.
• Approximating electron integrals using resolution of the identity (RI) is crucial for computational efficiency.

Purpose of the Study:

• To optimize auxiliary basis sets for RI-approximated explicitly correlated methods.
• To ensure compatibility with existing cc-pVnZ-F12 orbital basis sets.
• To minimize resolution of the identity errors in these calculations.

Main Methods:

• Optimization of auxiliary basis sets for elements H, B-Ne, and Al-Ar.
• Utilizing the resolution of the identity (RI) approximation for three- and four-electron integrals.
• Calculating atomization energies for 42 molecules and spectroscopic properties for diatomic molecules.

Main Results:

• Developed new auxiliary basis sets fully matched to cc-pVnZ-F12 orbital basis sets.
• Demonstrated very small resolution of the identity errors with the new auxiliary sets.
• Achieved accurate atomization energies and spectroscopic properties, validating the approach.

Conclusions:

• The optimized auxiliary basis sets are highly effective for explicitly correlated MP2-F12 and CCSD-F12 calculations.
• These sets enable accurate and efficient computation of molecular properties, including potential energy surfaces.
• The findings facilitate more reliable theoretical predictions in quantum chemistry.