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DOE OSTI · 1831064

Spin–Orbit Natural Transition Orbitals and Spin-Forbidden Transitions

Feng, Rulin·Yu, Xiaojuan·Autschbach, Jochen
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Abstract

Natural transition orbitals (NTOs) are in widespread use for visualizing and analyzing electronic transitions. Here, the present work introduces the analysis of formally spin-forbidden transitions with the help of complex-valued spin-orbit (SO) NTOs. The analysis specifically focuses on the components in such transitions that cause their intensity to be non-zero because of SO coupling. Transition properties such as transition dipole moments are partitioned into SO-NTO hole-particle pairs, such that contributions to the intensity from specific occupied and unoccupied orbitals are obtained. The method has been implemented within the restricted active space (RAS) self-consistent field wave function theory framework, with SO coupling treated by RAS state interaction. SO-NTOs have a broad range of potential applications, which is illustrated by the T 2 -S 1 state mixing in pyrazine, spin-forbidden vs. spin-allowed 4f–5d transitions in the Tb 3+ ion, and the phosphorescence of tris(2-phenylpyridine) iridium [Ir(ppy) 3 ].

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Feng, Rulin, Yu, Xiaojuan, Autschbach, Jochen. 2021-11-18. Spin–Orbit Natural Transition Orbitals and Spin-Forbidden Transitions. https://doi.org/10.1021/acs.jctc.1c00776

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