Modeling nonadiabatic spin dynamics in single-ion magnets with crystal field Hamiltonian

Predicting spin relaxation and decoherence in single-ion magnets (SIMs) is crucial for designing practical spin-based materials for quantum information science applications, including quantum memory devices and quantum computing. A detailed understanding of the spin relaxation and decoherence pathways, including those mediated by couplings between the vibrational and spin degrees of freedom, is necessary to design new materials with long spin relaxation and coherence times. From the theoretical standpoint, this requires accurate modeling of the long time-scale electron and nuclear dynamics of actual molecular magnets with dozens of atoms, which is outside the capabilities of modern computational methods. To develop such capabilities, we aim to replace the ab initio electronic structure Hamiltonian used in the nonadiabatic molecular dynamics simulations with the crystal field Hamiltonian (CFH). Extremely fast electronic structure calculations with CFH will allow us to model the spin relaxation in large realistic SIMs. To achieve this goal, it is necessary to accurately parametrize CFH and interface it with nonadiabatic molecular dynamics. We will present the current progress on the development of this CFH-based nonadiabatic molecular dynamics to model spin relaxation in SIMs.