Source code (Perl) for 10 MASS potentials can be downloaded here (3.4Mb).
Tong Liu and Zheng Wang. MASS: predict the global qualities of individual protein models using random forests and novel statistical potentials. BMC Bioinformatics (2020) 21:246.
Tong Liu and Zheng Wang. SOV_refine: A further refined definition of segment overlap score and its significance for protein structure similarity. Source Code for Biology and Medicine,(2018) 13:1.