Radical pair time evolution

An interactive teaching example using a remote Python API and RadicalPy. Adjust the model parameters to plot spin-state populations versus time at a fixed magnetic field.

Model assumptions

• Two electron spins, with one isotropically coupled ¹H nucleus.
• Selectable singlet or triplet initial state, with exponential kinetic model.
• Scalar exchange coupling J and dipolar coupling D (both in mT), using RadicalPy conventions.
• Fixed applied magnetic field, with time on the horizontal axis.
• The rate applies uniform exponential survival exp(−kt). It does not alter coherent spin mixing or represent spin-selective recombination.
• Singlet + T+ + T0 + T− = 1 for the unrecombined ensemble; total triplet is the sum of the three substates.
• This is a demonstration model, not a fit to experimental data.

For research use, validate the kinetic scheme, units, normalisation, and simulation settings against the relevant physical model and RadicalPy version.