TWA versus semiclassical unitary approximation for spin-like systems

We analyze the stable and unstable evolution of spin-like systems in the framework of the Truncated Wigner and Unitary Approximations, and test the dependence of the time scale where the classical evolution determines the dynamics of a quantum system on the semiclassical parameter. - Highlights: • Semiclassical unitary approach (SUA) is applied for analysis of large-spin dynamics. • Stable and unstable evolution of spin systems in the semiclassical limit is discussed. • A comparative analysis of SUA and Truncated Wigner Approximation is performed.