  Based on the results of the second author, we define an equivariant version
of Lee and Bar-Natan homology for periodic links and show that there exists an
equivariant spectral sequence from the equivariant Khovanov homology to
equivariant Lee homology. As a result we obtain new obstructions for a link to
be periodic. These obstructions generalize previous results of Przytycki and of
the second author.
