Hi guys, I've been using XPLOR-NIH for a while now but until recently had not come across the following error:
--> ERROR: matrix is not a rotation matrix. This seems to happen when I use a torsion angle dynamics protocol, but change my noe potential from: potential all soft to: potential all square The protocol I'm using for simulated annealing works perfectly when I use the "soft" noe potential function, and dies with the aforementioned error if this is changed to "square". I've tried to isolate the problem, but all I can conclude at this stage is that "soft" lets things work, and "square" doesn't. Can anyone give me the low-down on what silly mistake I have probably made? I did find something about ARIA/CNS giving this error when using a torsion angle dynamics protocol, and that it can be a timestep issue. I feel quite happy with a 0.015 ps timestep and find that reducing it to less desirable values fails to fix the problem. Thanks in advance, Haydyn -- ----------------------------------------------- Haydyn Mertens PhD student Department of Biochemistry University of Melbourne Australia
