For non-covalently bound clusters of molecules, the RMSD bias has a tendency to cause clusters to dissociate, so there is a specialized non-covalent interactions (NCI) mode which performs only six MTD runs per cycle, with reduced kpush and alpha settings, and adds an ellipsoid constraining potential which forces the molecules to remain near each other. Such constraining potentials can also be added manually to CREST runs when NCI mode is turned off, if desired. The wscal keyword takes a numerical argument, and allows the user to scale the size of an automatically generated constraining potential. For example, wscal 0.75 would make the constraining potential three-quarters of its default radius, thus forcing monomers to remain closer to each other. Additionally, the nmtd keyword can set the number of metadynamics runs per cycle to a different number than the defaults. CREST has an entropy mode, invoked with the v4 keyword, which aims to fill out the ensemble as much as possible, thus maximizing computed entropy. This is the only runtype of CREST which starts metadynamics runs from more than one conformer in a cycle. CREST also has options for runtypes that only use part of its functionality. Two examples are the screen function, which will take an already generated ensemble or trajectory and sort and optimize the individual structures, while discarding those of high energy, and the rmsd function, which will simply compute the RMSD between two structures. Unfortunately, the CREST documentation does not provide a means to adjust the values of kpush or alpha.