  The dynamical transverse magnetic Kohn-Sham susceptibility calculated within
time-dependent density functional theory shows a fairly linear behavior for a
finite energy window. This observation is used to propose a scheme where the
computation of this quantity is greatly simplified. Regular simulations based
on static density functional theory can be used to extract the dynamical
behavior of the magnetic response function. Besides the ability to calculate
elegantly damping of magnetic excitations, we derive along the way useful
equations giving the main characteristics of these excitations: effective
$g$-factors and the resonance frequencies that can be accessed experimentally
using inelastic scanning tunneling spectroscopy or spin-polarized electron
energy loss spectroscopy.
