Multiple quantum dynamics in a system of dipole-coupling spins in solid
  A perturbation method deals with dipolar coupling spins in solids is presented. As examples of the application the method, the multile-quantum coherence dynamics in clusters of a linear chain of four nuclear spins and a ring of six spins coupled by dipole-dipole interaction are considered. The calculated 0Q- and 2Q intensities in a linear chain of four nuclear spins and 6Q intensity in a ring of six spins vs the duration of the preparation period agree well with the exact solutions (for linear chain of four nuclear spins) and simulation data (for linear chain of four nuclear spins and a ring of six spin). 
G.B.Furman, S.D.Goren, V.M.Meerovich, V.L.Sokolovsky, and S.William