Comparison of Variational and Perturbative Spin-Orbit Coupling within Two-Component CASSCF

Area of Science:

• Computational chemistry
• Quantum chemistry
• Materials science

Background:

• Spin-orbit coupling (SOC) modeling is computationally expensive, hindering research in spin-driven processes and f-block elements.
• Accurate and scalable multiconfigurational SOC methods are needed for complex chemical systems.

Purpose of the Study:

• To introduce and evaluate a new implementation of perturbative spin-orbit coupling within the scalar-relativistic two-component CASSCF framework (srX2C-CASSCF-SO).
• To assess the accuracy and limitations of the srX2C-CASSCF-SO method for computational chemistry applications.

Main Methods:

• Implementation of perturbative spin-orbit coupling (SOC).
• Utilized scalar-relativistic two-component Complete Active Space Self-Consistent Field (srX2C-CASSCF) method.
• Performed benchmark calculations to validate the srX2C-CASSCF-SO approach.

Main Results:

• The srX2C-CASSCF-SO method provides a new approach for incorporating SOC effects in large-scale computational studies.
• Benchmark calculations offer insights into the accuracy and limitations of this specific SOC treatment.
• The study lays groundwork for more efficient SOC modeling in complex systems.

Conclusions:

• The developed srX2C-CASSCF-SO method offers a valuable tool for studying systems where SOC is significant.
• Understanding the limitations of different SOC treatments is essential for reliable computational predictions.
• This work contributes to advancing computational methods for f-block chemistry and materials science.