Floquet Quantum theory Spin systems Spin-s systems All to alls Chaotics Collective spin Crystal phasis Crystals Errors Excited states Field natures Geometry Hamiltonians In-phase Ising model Mean-field Multi-body interactions Optimal state Perturbation techniques Phase space geometry Phase space methods Phase spaces Phase transitions Quantitative prediction Quantum chemistry Quantum metrology Quantum simulations Small variations Spin 1/2