Quantum mechanical spin dynamics of a molecular magnetoreceptor

Lachlan P Lindoy; Thomas P Fay; David E Manolopoulos

doi:10.1063/5.0006411

Quantum mechanical spin dynamics of a molecular magnetoreceptor

J Chem Phys. 2020 Apr 30;152(16):164107. doi: 10.1063/5.0006411.

Authors

Lachlan P Lindoy¹, Thomas P Fay¹, David E Manolopoulos¹

Affiliation

¹ Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom.

PMID: 32357766
DOI: 10.1063/5.0006411

Abstract

Radical pair recombination reactions are known to be sensitive to extremely weak magnetic fields and can therefore be said to function as molecular magnetoreceptors. The classic example is a carotenoid-porphyrin-fullerene (C^•+PF^•-) radical pair that has been shown to provide a "proof-of-principle" for the operation of a chemical compass [K. Maeda et al., Nature 453, 387 (2008)]. Previous simulations of this radical pair have employed semiclassical approximations, which are routinely applicable to its 47 coupled electronic and nuclear spins. However, calculating the exact quantum mechanical spin dynamics presents a significant challenge and has not been possible until now. Here, we use a recently developed method to perform numerically converged simulations of the C^•+PF^•- quantum mechanical spin dynamics, including all coupled spins. A comparison of these quantum mechanical simulations with various semiclassical approximations reveals that, while it is not perfect, the best semiclassical approximation does capture essentially all of the relevant physics in this problem.