  We apply diffusion quantum Monte Carlo (DMC) to a broad set of solids,
benchmarking the method by comparing bulk structural properties (equilibrium
volume and bulk modulus) to experiment and DFT based theories. The test set
includes materials with many different types of binding including ionic,
metallic, covalent and van der Waals. We show that, on average, the accuracy is
comparable to or better than that of density functional theory (DFT) when using
the new generation of functionals, including one hybrid functional and two
dispersion corrected functionals. The excellent performance of quantum Monte
Carlo (QMC) on solids is promising for its application to heterogeneous systems
and high-pressure/high density conditions. Important to the results here is the
application of a consistent procedure with regards to the several
approximations that are made, such as finite-size corrections and
pseudo-potential approximations. This test set allows for any improvements in
these methods to be judged in a systematic way.
