On Sat, Jul 10, 2010, llduan.itcs.ecnu.edu.cn wrote:
> I am using the ff02 polarizable force field with TIP3P water model
>
> NSTEP ENERGY RMS GMAX NAME NUMBER
> 500 -9.9285E+14 8.2626E+17 1.0696E+20 O 995
> BOND = 27217.7852 ANGLE = 43.6487 DIHED = 133.3883
> VDWAALS = 27835.5582 EEL = -4418425.3325 HBOND = 0.0000
> 1-4 VDW = 75.0408 1-4 EEL = 888.0260 RESTRAINT = 0.0000
> EPOLAR = *************
> Dipole convergence: rms = 0.349E+12 temperature = 0.00
I'm guessing that you don't have SHAKE turned on(?), and that you have
minimized to a spot where atoms are on top of each other (and in addition, you
have a "polarization catastrophe").
First, are you sure you need/want to be using a rarely-used polarizable
potential? Generally, I would recommend setting up and equilibrating your
system with a non-polarizable potential (e.g. ff03 or ff99SB), and only
switching over to ff02 once you have good geometries and velocities. And even
there, use SHAKE when minimizing a solvated system.
And of course, the usual advice: if/when you have problems, run a short run,
setting ntpr and ntwx to small numbers (usually 1). Use a visualization
program to look at the results, to try to identify the problem. In your
case, atom 995 is probably the culprit.
....dac
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Received on Sat Jul 10 2010 - 06:00:08 PDT
