Classical spin dynamics based on SU(N) coherent states

We introduce a classical limit of the dynamics of quantum spin systems based on coherent states of SU(N), where N is the dimension of the local Hilbert space. This approach, which generalizes the well-known Landau-Lifshitz dynamics from SU(2) to SU(N), provides a better approximation to the exact quantum dynamics for a large class of realistic spin Hamiltonians, including S >= 1 systems with large single-ion anisotropy and weakly coupled multispin units, such as dimers or trimers. We illustrate this idea by comparing the spin structure factors of a single-ion S = 1 model that are obtained with the SU(2) and SU(3) classical spin dynamics against the exact solution.

Automated summary

This paper introduces a classical limit of the dynamics of quantum spin systems based on coherent states of SU(N), generalizing the Landau-Lifshitz dynamics from SU(2) to SU(N). This approach provides a better approximation to the exact quantum dynamics for a variety of realistic spin Hamiltonians. Comparing the spin structure factors of an S=1 model obtained with SU(2) and SU(3) classical spin dynamics against the exact solution illustrates the effectiveness of this idea.