Inertial dynamics and equilibrium correlation functions of magnetization at short times

The method of moments is developed and employed to analyze the equilibrium correlation functions magnetization ferromagnetic nanoparticles in case inertial dynamics. based on Taylor series expansion estimation coefficients. This significantly reduces complexity analysis functions. Analytical expressions are derived for first three coefficients longitudinal transverse uniaxial magnetocrystalline anisotropy with a magnetic field. limiting cases very strong negligibly weak external fields considered. Gordon sum rule dynamics discussed. In addition, we show that finite analytic can be used as simple satisfactory approximation numerical calculation at short times.