Hydrogen-Atom Electronic Basis Sets for Multicomponent Quantum Chemistry.

Area of Science:

• Quantum chemistry
• Computational chemistry
• Theoretical chemistry

Background:

• Multicomponent methods incorporate nuclear quantum effects into quantum chemistry.
• Standard methods often require large electronic basis sets for accurate electron-nuclear correlation, especially for hydrogen nuclei.
• Existing correlation-consistent basis sets are not optimized for nuclear properties.

Purpose of the Study:

• To develop new electronic basis sets optimized for multicomponent methods.
• To improve the accuracy and efficiency of calculations involving quantum hydrogen nuclei.
• To address the limitations of standard basis sets in describing electron-nuclear correlation.

Main Methods:

• Introduction of cc-pV*n*Z-mc, a new series of correlation-consistent electronic basis sets for hydrogen atoms.
• Optimization of additional basis functions to reproduce multicomponent density functional theory protonic densities.
• Evaluation of the new basis sets for protonic densities, proton affinities, and protonic excitation energies.

Main Results:

• The cc-pV*n*Z-mc basis sets yield improved protonic densities compared to standard sets.
• Fewer electronic basis functions are needed with cc-pV*n*Z-mc for comparable or better accuracy.
• The new basis sets accurately reproduce proton affinities and protonic excitation energies without specific optimization for these properties.

Conclusions:

• The cc-pV*n*Z-mc basis sets offer a more efficient and accurate approach for multicomponent calculations.
• These basis sets enhance the computational feasibility of studying larger systems with nuclear quantum effects.
• The optimization strategy effectively improves the description of electron-nuclear correlation in multicomponent methods.