The OccQP software was first described in the article "Optimization of site-occupancies in minerals using quadratic programming" by S.E. Wright, J.A. Foley, and J.M. Hughes, American Mineralogist 85 (2000), 524-531. Additional details on using OccQP are available in this PDF manual.
OccQP was designed for use within the Matlab mathematical computing environment. The most recent major OccQP update occurred in 2006 and the resulting Matlab p-code file was verified to work with Matlab releases as late as 2010. That version can be downloaded by using your browser's "Save as" or "Save target as" feature to select this file (Version 0.51). Later releases of Matlab may work better with this file (Version 0.52), which includes a few adjustments needed in 2011. To use the software, rename the downloaded file 'occqp.p' (without the quotation marks) and place it in a directory on your Matlab path.
OccQP is no longer supported by the authors.