Self-consistent treatment of spin-orbit interactions with efficient Hartree-Fock and density functional methods

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Scalar relativistic and spin-orbit (SO) effects are crucial for accurately describing the electronic structure of heavy elements.
• Standard computational methods often neglect these effects, limiting their applicability to heavier systems.
• Efficient algorithms are needed to incorporate these effects without prohibitive computational cost.

Purpose of the Study:

• To present efficient self-consistent field (SCF) schemes that include both scalar relativistic effects and spin-orbit (SO) interactions.
• To implement these schemes within the TURBOMOLE program system.
• To demonstrate the relevance of SO effects for the electronic structure and stability of heavy element systems.

Main Methods:

• Development of two-component formalisms to handle SO interactions.
• Utilization of effective core potentials (ECPs) to reduce computational complexity.
• Application of the resolution-of-the-identity (RI) approximation (RI-J for DFT, RI-JK for HF/hybrid-DFT) for efficient calculation of integrals.
• Implementation within the TURBOMOLE quantum chemistry software.

Main Results:

• Efficient SCF schemes for scalar relativistic and SO effects at Hartree-Fock (HF) and density functional theory (DFT) levels.
• Demonstrated efficiency for large systems, exemplified by calculations on Pb54.
• Illustrated the significant impact of SO effects on the electronic structure and stability of lead (Pb) and polonium (Po) clusters.

Conclusions:

• The developed computational schemes provide an efficient means to include relativistic effects in electronic structure calculations.
• These methods are essential for accurate modeling of heavy element chemistry.
• The study highlights the importance of SO effects for understanding the properties of systems containing heavy atoms.