Two citation papers describing the capabilities and future plans for the code have been published.
J. Kim et al J. Phys.: Condens. Matter 30 195901 (2018), https://doi.org/10.1088/1361-648X/aab9c3. A follow-up review describing the most recent developments is P. Kent et al. J. Chem Phys. 152 174105 (2020), https://doi.org/10.1063/5.0004860 . Both papers are open access. Please cite these papers when using QMCPACK.