Relativistic correlating basis sets for lanthanide atoms from Ce to Lu

Area of Science:

• Quantum chemistry
• Atomic and molecular physics
• Computational chemistry

Background:

• Accurate description of electron correlation is crucial for understanding chemical properties.
• Lanthanide atoms present unique challenges due to their complex electronic structures, particularly the 4f subshell.
• Existing basis sets may not adequately capture the correlation effects in these systems, especially for molecular applications.

Purpose of the Study:

• To develop and present new Contracted Gaussian-type function (CGTF) basis sets for lanthanide atoms (Ce-Yb, Lu).
• To specifically address the description of 4f subshell correlation and the inclusion of 6s and 5d subshell correlation.
• To provide efficient and accurate basis sets for computational chemistry studies involving lanthanides.

Main Methods:

• Development of CGTF sets using a segmented contraction scheme for efficiency.
• Optimization of contraction coefficients and exponents by minimizing deviations from accurate natural orbitals.
• Inclusion of relativistic effects through the third-order Douglas-Kroll approximation in reference calculations.
• Application of the developed basis sets in all-electron and model core potential calculations.

Main Results:

• New CGTF sets were successfully developed for lanthanide atoms from Ce to Yb, including specific sets for Lu.
• The basis sets effectively describe the 4f subshell correlation and incorporate correlation for the 6s and 5d subshells.
• Calculations on the diatomic CeO molecule using these sets yielded spectroscopic constants in good agreement with experimental data.

Conclusions:

• The developed CGTF sets offer a significant improvement for describing electron correlation in lanthanide atoms.
• These basis sets are efficient and accurate, suitable for molecular calculations involving lanthanides.
• The study validates the utility of the new basis sets through successful application to CeO.