Dynamical model for spin-crossover solids. I. Relaxation effects in the mean-field approach

A stochastic cooperative dynamics of the Ising-like Hamiltonian describing the equilibrium properties of the spin-crossover solids is derived from the Glauber approach, where an appropriate choice of the microscopic dynamics is made with respect to experimental features. The model is used here in the mean-field approach, and supports the previous phenomenological dynamic equations. The expected sigmoidal shape of the relaxation curves from high-spin to low-spin states after photoexcitation is obtained, and the kinetic character of the thermal hysteresis loops (inherent to the experimental data) is properly accounted for.