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Message 438: error - PMF constraints failed to converge

The constraints in the potential of mean force algorithm have not converged in the permitted number of cycles. (The SHAKE algorithm for PMF constraints is iterative.) 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. It is unlikely that simply increasing the iteration number will cure the problem, but you can try: follow standard user response to increase the parameter mxshak. 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?



W Smith 2003-05-12