  Using continuum based simulations we show that a rich variety of skyrmion
liquid crystal states can be realized in the presence of a periodic obstacle
array. As a function of the number of skyrmions per obstacle we find hexagonal,
square, dimer, trimer and quadrimer ordering, where the $n$-mer structures are
a realization of a molecular crystal state of skyrmions. As a function of
external field and obstacle radius we show that there are transitions between
the different crystalline states as well as mixed and disordered structures. We
discuss how these states are related to commensurate effects seen in other
systems, such as vortices in type-II superconductors and colloids interacting
with two dimensional substrates.
