  As opposed to traditional methods of multiple-quantum NMR spectroscopy
authors of the article [G.A. Alvarez, D. Suter, Phys. Rev. A 84, 012320 (2011)]
generated the effective double-quantum Hamiltonian, with the slight adding
usual secular dipole-dipole Hamiltonian to the first one at the stage of the
correlations preparing (so the perturbation appeared). At this framework the
width of MQ spectra reveals tending to any constant amount with the growing up
of the time. Also there were shown that the spectral width decreases with
increasing perturbation strength. The growing up of the cluster size as it was
supposed by G.A. Alvarez and D. Suter was restricted by mentioned perturbation.
We are assuming an alternative explanation. The growing up of cluster size
still goes on but the width of MQ spectrum becomes stable because of different
decay rate of MQ-spectral components in dependence on theirs location in
spectrum. Here we are calculating the widths of MQ spectra in dependence on the
time of "preparation" for different values of the perturbation strength and by
this way we get the dependence of stabilized amount of MQ-spectrum width on
mentioned strength. So, the excellent compliance obtains with the analogues
experimental relation observed in Ref. [Phys. Rev. A 84, 012320 (2011)].
