Correlation consistent basis sets for explicitly correlated wavefunctions: pseudopotential-based basis sets for the...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Explicitly correlated F12 methods significantly reduce basis set requirements.
• Accurate treatment of outer-core d-electron correlation is crucial for post-d main group elements.
• Previous basis sets were not optimized for F12 calculations involving these elements.

Purpose of the Study:

• To develop and optimize new correlation consistent basis sets for F12 calculations.
• To enable accurate and efficient computation of spectroscopic properties for Ga-Rn elements.
• To assess the performance of these new basis sets in explicitly correlated coupled-cluster calculations.

Main Methods:

• Optimization of correlation consistent basis sets (cc-pVnZ-PP-F12) for F12 calculations.
• Development of matching auxiliary basis sets for density fitting.
• Construction of basis sets for use with small-core relativistic pseudopotentials.
• Benchmark coupled-cluster singles and doubles with perturbative triples [CCSD(T)-F12b] calculations.

Main Results:

• New basis sets (cc-pVnZ-PP-F12) are optimized for Ga-Rn elements.
• F12 calculations with new sets show high accuracy, comparable to larger conventional basis sets.
• Efficient recovery of outer-core d-electron correlation effects was achieved.
• Spectroscopic properties of diatomic molecules involving 4p, 5p, and 6p elements were accurately computed.

Conclusions:

• The new cc-pVnZ-PP-F12 basis sets are highly effective for explicitly correlated calculations.
• These basis sets offer a more efficient route to accurate results for post-d main group elements.
• The developed sets advance the capability of computational chemistry for heavy element systems.