Density Functional and Basis Set Dependence of Hydrated Ln(III) Properties

Area of Science:

• Computational chemistry
• Quantum chemistry
• Lanthanide chemistry

Background:

• Accurate theoretical descriptions of lanthanide (Ln) complexes are crucial for understanding their properties.
• Various computational methods and basis sets are available, but their performance for lanthanides needs rigorous evaluation.

Purpose of the Study:

• To benchmark different quantum chemical methods and basis sets for lanthanide complexes.
• To assess the reliability of common evaluation metrics like lanthanide contraction.
• To propose improvements for describing lanthanide electronic structure.

Main Methods:

• Benchmark studies of La(H2O)9(3+) and Lu(H2O)9(3+) complexes.
• Application of local density approximation, generalized gradient approximation (GGA), meta-GGA, and hybrid functionals.
• Utilized small- and large-core relativistic effective core potentials and associated basis sets.
• Analysis of basis set dependence and natural population analysis (NPA).

Main Results:

• The lanthanide contraction is an inadequate metric for assessing the quality of computational methods due to error cancellation.
• Basis set dependence was significant, highlighting the importance of specific functions for describing lanthanide atomic orbitals.
• An alternative valence space partitioning, including 6s6p5d4f natural atomic orbitals, was proposed for improved electrostatic description.

Conclusions:

• Standard computational methods require careful selection of basis sets for accurate lanthanide property prediction.
• Lanthanide contraction alone is insufficient for validating computational approaches.
• The proposed valence space partitioning offers a more reliable way to analyze electrostatic properties in lanthanide systems.