Electron spin relaxation in radical pairs: Beyond the Redfield approximation

Abstract

Relaxation processes can have a large effect on the spin selective electron transfer reactions of radical pairs. These processes are often treated using phenomenological relaxation superoperators or with some model for the microscopic relaxation mechanism treated within Bloch-Redfield-Wangsness theory. Here, we demonstrate that an alternative perturbative relaxation theory, based on the Nakajima-Zwanzig equation, has certain advantages over Redfield theory. In particular, the Nakajima-Zwanzig equation does not suffer from the severe positivity problem of Redfield theory in the static disorder limit. Combining the Nakajima-Zwanzig approach consistently with the Schulten-Wolynes semiclassical method, we obtain an efficient method for modeling the spin dynamics of radical pairs containing many hyperfine-coupled nuclear spins. This is then used to investigate the spin-dependent electron transfer reactions and intersystem crossing of dimethyljulolidine-naphthalenediimide (DMJ-NDI) radical ion pairs. By comparing our simulations with experimental data, we find evidence for a field-independent contribution to the triplet quantum yields of these reactions which cannot be explained by electron spin relaxation alone.

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Cited by in corpus (8)

• The origin of chirality induced spin selectivity in photo-induced electron transfer
• Chirality Induced Spin Coherence in Electron Transfer Reactions
• Simulating Open Quantum System Dynamics on NISQ Computers with Generalized Quantum Master Equations
• A simple improved low temperature correction for the hierarchical equations of motion
• Spin relaxation in radical pairs from the stochastic Schrödinger equation
• Overcoming positivity violations for density matrices in surface hopping
• Quantum mechanical spin dynamics of a molecular magnetoreceptor
• Spinterface-like mechanism of the chirality-induced spin selectivity in donor chiral-bridge acceptor complexes