The quaternion algorithm has failed to converge. If the
maximum number of permitted iterations is exceeded, the program
terminates. Possible causes include: a bad starting configuration; too
large a time step used; incorrect force field specification; too high
a temperature; inconsistent constraints involving shared atoms etc.
Action:
Corrective action depends on the cause. Try reducing
the timestep or running a zero kelvin structure optimization for a
hundred timesteps or so. It is unlikely that simply increasing the
iteration number will cure the problem, but you can try: follow the
standard user response to increase the parameter mxquat. But the
trouble is much more likely to be cured by careful consideration of
the physical system being simulated. For example, is the system
stressed in some way? Too far from equilibrium?