Hi Agostino,
On 29/03/2012, at 4:33 AM, Agostino Bruno wrote:
> Dear all,
>
> I am writing you because I tried to parametrize a ligand using xleap. I
> parametrized a ligand in a TIP3PBOX with 1 Cl- atom (so as to neutralize the
> net charge). During the parametrization stage everything seems work well. At
> the end I obtained the ligand.prmtop, ligand.inpcrd, and ligand.pdb files.
> First of all I checked the generated fiels using vmd, and everything seems ok.
> After that I tried to minimize the ligand using Amber11, I used one processor
> and the command line:
>
> sander -i minimization.in -o minimization.out -p prova.prmtop -c prova.inpcrd
> -ref prova.inpcrd -r mini_restrt.
>
> But Amber almost immediately crashed with this error message:
>
> Segmentation fault.
Looking at the mdout file you attached, I see that the 1-4 VDW and 1-4 electrostatic (the latter shown as 1-4 EEL) energy terms are given as "NaN", as are the RMS gradient and the total energy. This likely means one of two things. Either two atoms in a 1-4 relationship are on top of each other -- in which case the denominators in the expressions for electrostatic and van der Waals terms go to zero -- or you have bogus parameters, typically a zero value where a non-zero value is expected. Since both electrostatic and van der Waals terms are affected, I'd suspect the former.
In short, check your structure for overlapping atoms.
Hope that helps,
Ben
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Received on Wed Mar 28 2012 - 13:30:03 PDT
