  Barnett relaxation, first described by Purcell in 1979, appears to play a
major role in the alignment of grains with the interstellar magnetic field. In
1999, Lazarian and Draine proposed that Barnett relaxation and its relative,
nuclear relaxation, can induce grains to flip. If this thermal flipping is
rapid, then the dynamical effect of torques that are fixed relative to the
grain body can be greatly reduced. To date, detailed studies of Barnett
relaxation have been confined to grains exhibiting dynamic symmetry. In 2003,
Weingartner argued that internal relaxation cannot induce flips in any grains,
whether they exhibit dynamic symmetry or not. In this work, we develop
approximate expressions for the dissipation rate and diffusion coefficient for
Barnett relaxation. We revisit the issue of internally induced thermal
flipping, finding that it cannot occur for grains with dynamic symmetry but
does occur for grains lacking dynamic symmetry.
