Basis set and method dependence in atoms in molecules calculations

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Modeling

Background:

• Accurate characterization of weak hydrogen bonds is crucial in various chemical and biological systems.
• Atoms in Molecules (AIM) theory provides valuable insights into chemical bonding through electron density analysis.
• The choice of basis sets in quantum chemical calculations can influence the derived molecular properties.

Purpose of the Study:

• To investigate the influence of different basis sets on Atoms in Molecules (AIM) parameters for weak hydrogen-bonded systems.
• To evaluate the reliability of various computational methods and basis sets for describing hydrogen bond characteristics.

Main Methods:

• Hartree-Fock (HF) and Density Functional Theory (DFT/B3LYP) calculations were employed.
• Three model complexes representing weak hydrogen bonds were studied: F(3)CH...NH(3), F(3)CH...NCH, and FCCH...NH(3).
• Analysis focused on AIM parameters at the bond critical point of the hydrogen bond.

Main Results:

• AIM parameters at the hydrogen bond critical point were found to be largely independent of the computational method and basis set used.
• The smallest Dunning-type basis sets (cc-pVDZ, aug-cc-pVDZ) may yield less accurate results.
• Medium-sized Pople-type basis sets provided results comparable to larger Dunning-type basis sets.

Conclusions:

• The choice of basis set has a limited impact on the calculated AIM parameters for weak hydrogen bonds.
• Medium-sized Pople-type basis sets offer a good balance between accuracy and computational cost for studying these systems.
• These findings suggest that reliable analysis of weak hydrogen bonds using AIM theory is achievable with moderately sized basis sets.