[phenixbb] Check for radiation-induced reduction of a disulfide bond

I'm working with one protein, crystallized in oxidized form, which exhibits negative density in the Fo-Fc map at the center of the disulfide bond. As a test of radiation-induced reduction during data collection, I'd like to do a trial refinement described in a previous work from literature, where SG sulfurs of involved cysteines were refined without van der Waals interactions to monitor distances of these atoms. How can I do this calculation in Phenix? Thanks in advance