# An improved semiclassical theory of radical pair recombination reactions.

@article{Manolopoulos2013AnIS, title={An improved semiclassical theory of radical pair recombination reactions.}, author={David E. Manolopoulos and Peter Hore}, journal={The Journal of chemical physics}, year={2013}, volume={139 12}, pages={ 124106 } }

We present a practical semiclassical method for computing the electron spin dynamics of a radical in which the electron spin is hyperfine coupled to a large number of nuclear spins. This can be used to calculate the singlet and triplet survival probabilities and quantum yields of radical recombination reactions in the presence of magnetic fields. Our method differs from the early semiclassical theory of Schulten and Wolynes [J. Chem. Phys. 68, 3292 (1978)] in allowing each individual nuclear…

## 30 Citations

### Asymmetric recombination and electron spin relaxation in the semiclassical theory of radical pair reactions.

- PhysicsThe Journal of chemical physics
- 2014

The intriguing biphasic behaviour that has been observed in the effect of an Earth-strength magnetic field on the time-dependent survival probability of the photo-excited C(·+)PF(·-) radical pair arises from a delicate balance between its asymmetric recombination and the relaxation of the electron spin in the carotenoid radical.

### An efficient quantum mechanical method for radical pair recombination reactions.

- PhysicsThe Journal of chemical physics
- 2016

Calculations on a strongly coupled radical pair with Z>106 show that the singlet yield can be converged to graphical accuracy using just M=200 samples, resulting in a speed up by a factor of >5000 over a standard deterministic calculation.

### Quantum mechanical spin dynamics of a molecular magnetoreceptor.

- PhysicsThe Journal of chemical physics
- 2020

A recently developed method is used to perform numerically converged simulations of the C•+PF•- quantum mechanical spin dynamics, including all coupled spins, and reveals that the best semiclassical approximation does capture essentially all of the relevant physics in this problem.

### Radical pair intersystem crossing: Quantum dynamics or incoherent kinetics?

- PhysicsThe Journal of chemical physics
- 2019

It is shown, in particular, how the finite lifetime of the radical pair spin states, as well as any additional spin-state dephasing, leads to incoherent intersystem crossing.

### How quantum is radical pair magnetoreception?

- PhysicsFaraday discussions
- 2019

It is found that semiclassical approximations to the spin dynamics of radical pairs only provide a satisfactory description of the anisotropic product yields when there is no electron spin-spin coupling, a situation unlikely to be consistent with a magnetic sensing function.

### Spin-selective electron transfer reactions of radical pairs: Beyond the Haberkorn master equation.

- Physics, ChemistryThe Journal of chemical physics
- 2018

By performing simulations of radical pair reactions with the exact hierarchical equations of motion method, it is demonstrated that the master equations provide a very accurate description of radical pairs undergoing spin-selective non-adiabatic electron transfer reactions.

### Spin-dependent charge recombination along para-phenylene molecular wires.

- PhysicsThe Journal of chemical physics
- 2017

An efficient new quantum mechanical method for radical pair recombination reactions is used to study the spin-dependent charge recombination along PTZ•+-Phn-PDI•- molecular wires and finds that the triplet recombination rate constant decreases exponentially with the length of the wire, consistent with the superexchange mechanism of charge recombinations.

### Monte-Carlo wavefunction approach for the spin dynamics of recombining radicals

- PhysicsNew Journal of Physics
- 2020

We adapt the Monte-Carlo wavefunction (MCWF) approach to treat the open-system spin dynamics of radical pairs subject to spin-selective recombination reactions. For these systems, non-Lindbladian…

### Simple and Accurate Method for Central Spin Problems.

- PhysicsPhysical review letters
- 2018

We describe a simple quantum mechanical method that can be used to obtain accurate numerical results over long timescales for the spin correlation tensor of an electron spin that is hyperfine coupled…

### On the low magnetic field effect in radical pair reactions.

- Physics, ChemistryThe Journal of chemical physics
- 2018

A complete analysis of the low field effect in a radical pair containing a single proton and in aradical pair in which one of the radicals contains a large number of hyperfine-coupled nuclear spins finds that the new transitions that occur when the field is switched on are between S and T0 in both cases, and not between T± as has previously been claimed.

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