[gmx-users] Sanjay (Re: Energy minimization problem)

[Justin Lemkul]

On 5/10/15 3:28 PM, sanjay choubey wrote:
> HI,    I am running membrane protein dynamics. After energy minimization i am getting the following error. I am not getting how to rectify it.    Energy is minimized in fewer steps. Without proper minimization i cant proceed to next step of NVT run. Here is the error:  Steepest Descents:   Tolerance (Fmax)   =  1.00000e+03   Number of steps    =        50000Step=   14, Dmax= 1.2e-06 nm, Epot=  3.71240e+18 Fmax=         inf, atom= 842Stepsize too small, or no change in energy.Converged to machine precision,but not to the requested precision Fmax < 1000
> Double precision normally gives you higher accuracy.You might need to increase your constraint accuracy, or turnoff constraints alltogether (set constraints = none in mdp file)
> writing lowest energy coordinates.
> Steepest Descents converged to machine precision in 15 steps,but did not reach the requested Fmax < 1000.Potential Energy  =  3.7124040e+18Maximum force     =            inf on atom 842Norm of force     =            inf
>

Infinite force suggests a catastrophically bad starting configuration.

-Justin

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Justin A. Lemkul, Ph.D.
Ruth L. Kirschstein NRSA Postdoctoral Fellow

Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 629
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201

jalemkul at outerbanks.umaryland.edu | (410) 706-7441
http://mackerell.umaryland.edu/~jalemkul

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