A general method for the development of diabatic spin-orbit models for multi-electron systems.

Area of Science:

• Quantum chemistry
• Molecular dynamics
• Spectroscopy

Background:

• Spin-orbit (SO) coupling significantly impacts molecular quantum dynamics.
• Accurate modeling of SO coupling is challenging, especially for multi-electron systems.
• Existing diabatic SO models are often complex and system-specific.

Purpose of the Study:

• To develop a straightforward and generalizable approach for constructing diabatic spin-orbit (SO) models.
• To accurately represent multi-electron fine structure states and their SO interactions.
• To provide a method applicable to various spin states (S≠1/2) and molecular symmetries.

Main Methods:

• Expressing multi-electron states using Slater determinants of single-electron spinors.
• Deriving single-electron SO matrix elements via Taylor expansions in symmetry-adapted nuclear coordinates.
• Utilizing Slater-Condon rules to obtain multi-electron SO matrix elements from single-electron ones.
• Generating symmetry-adapted polynomials for matrix elements up to arbitrary order.

Main Results:

• A general and simplified method for constructing diabatic SO models for multi-electron systems.
• Accurate calculation of SO matrix elements and their symmetry properties.
• Demonstrated applicability to an abstract model and the photodissociation of methyl iodide (CH3I).
• High accuracy validated against existing analytic SO models.

Conclusions:

• The presented approach offers a significant advancement in modeling spin-orbit coupling in molecular systems.
• It provides a robust and versatile tool for theoretical chemists and physicists.
• This method facilitates more accurate predictions of molecular dynamics and spectroscopic properties.