Spin State Relaxation in Spin Crossover Molecules

Spin crossover (SCO) materials have drawn intense attention lately due to its unique ability to switch from low-spin (LS) to high-spin (HS) state by external stimuli. The potential applications are including but not limited to magnetic information storage or quantum computing. A typical HS state is a metastable state, it tends to have a long lifetime. Therefore, HS to LS relaxation time is a critical quantity in all application areas. In this study, we aim to build a model in a simple and straightforward manner and solve a master equation within the reduced density matrix (RDM) formalism and the golden rule expression. Density Functional Theory is used to obtain the energy and orbitals of each spin state. The spin-orbit coupling matrix elements (SOCMEs), which couple the different spin states, are calculated by a post-scf code, Molsoc0.1, developed by Chiodo et al. Demonstration of the relaxation dynamics with Fe⁺²(bpy)₃ molecule will be given.