Charge Transfer with a Spin. II: A Framework for Diabatization which Localizes Charge and Spin

Fuente: arXiv
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Main Authors: Kumar, Alok, Tao, Zhen, Jin, Zuxin, Subotnik, Joseph E., Qiu, Tian
Format: Preprint
Published: 2026
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author Kumar, Alok
Tao, Zhen
Jin, Zuxin
Subotnik, Joseph E.
Qiu, Tian
author_facet Kumar, Alok
Tao, Zhen
Jin, Zuxin
Subotnik, Joseph E.
Qiu, Tian
contents We investigate a diabatization procedure that localizes charges (in real space) and localizes spins (in spin space) for open-shell systems that exhibit charge transfer in the presence of spin-orbit coupling. The procedure is applied to a two-state crossing between pairs of Kramers-restricted doublet states (which can also be considered effectively a four-state crossing). To generate the relevant electronic states, we employ the recently developed electron/hole-transfer Dynamically-weighted State-Averaged Constrained CASSCF (eDSC/hDSC) method that treats systems with an odd number of electrons. To generate the relevant diabatic states, we employ a two-step optimization over complex-unitary rotations that sequentially maximizes dipole and spin moments through iterative Jacobi sweeps; the resulting update rules are effectively equivalent to those of approximate joint diagonalization (AJD) applied to charge and spin. The method converges rapidly and yields smooth diabatic potential energy surfaces that preserve dipole and spin properties (e.g., a slowly varying pseudospin texture) along the reaction coordinate while maintaining time-reversal symmetry.
format Preprint
id arxiv_https___arxiv_org_abs_2602_07750
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Charge Transfer with a Spin. II: A Framework for Diabatization which Localizes Charge and Spin
Kumar, Alok
Tao, Zhen
Jin, Zuxin
Subotnik, Joseph E.
Qiu, Tian
Chemical Physics
We investigate a diabatization procedure that localizes charges (in real space) and localizes spins (in spin space) for open-shell systems that exhibit charge transfer in the presence of spin-orbit coupling. The procedure is applied to a two-state crossing between pairs of Kramers-restricted doublet states (which can also be considered effectively a four-state crossing). To generate the relevant electronic states, we employ the recently developed electron/hole-transfer Dynamically-weighted State-Averaged Constrained CASSCF (eDSC/hDSC) method that treats systems with an odd number of electrons. To generate the relevant diabatic states, we employ a two-step optimization over complex-unitary rotations that sequentially maximizes dipole and spin moments through iterative Jacobi sweeps; the resulting update rules are effectively equivalent to those of approximate joint diagonalization (AJD) applied to charge and spin. The method converges rapidly and yields smooth diabatic potential energy surfaces that preserve dipole and spin properties (e.g., a slowly varying pseudospin texture) along the reaction coordinate while maintaining time-reversal symmetry.
title Charge Transfer with a Spin. II: A Framework for Diabatization which Localizes Charge and Spin
topic Chemical Physics
url https://arxiv.org/abs/2602.07750