Spin Dynamics in Radical Pairs pp 45-63 | Cite as

# Semiclassical Approximations

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## Abstract

In Chap. 2, we outlined the quantum mechanics which describes radical pair reactions, and demonstrated an efficient way to perform fully quantum mechanical simulations. However, the computational time required for these calculations scales exponentially with the number of nuclear spins in the radical pair, meaning there is a limit to the size of radical pair which may practically be treated in this way. Furthermore, including spin relaxation in quantum mechanical simulations is an extremely complex task. In order to avoid the scaling problem, and to allow a straightforward phenomenological account of relaxation, we have considered two semiclassical models of radical pair reactions, which will be presented in this chapter.

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