For ferromagnetic materials Spin-Phonon coupling strength is calculated using the approach proposed by Granado et al.(, Phys. Rev. B 60, 11879 (1999)). But in this approach saturation magnetization (Ms) value for ferromagnetic materials is applied which is not possible to achieve for pure anti-ferromagnetic materials. So is there any other approach to calculate spin-phonon coupling strength for anti-ferromagentic materials?