  The full spin density fluctuations (SDF) spectra in 3d paramagnetic metals
are analyzed from first principles using the linear response technique. Using
the calculated complete wavevector and energy dependence of the dynamic spin
susceptibility, we obtain the most important, but elusive, characteristic of
SDF in solids: on-site spin correlator (SC). We demonstrate that the SDF have a
mixed character consisting of interacting collective and single-particle
excitations of similar strength spreading continuously over the entire
Brillouin zone and a wide energy range up to femtosecond time scales. These
excitations cannot be adiabatically separated and their intrinsically
multiscale nature should be always taken into account for a proper description
of metallic systems. Overall, in all studied systems, despite the lack of local
moment, we found a very large SC resulting in an effective fluctuating moment
of the order of several Bohr magnetons.
