On Wed, Nov 07, 2012, Baptiste Legrand wrote:
> During the
> calculations on a specific compound, the temperature is not controled
> and "vlimit exceeded" errors occured during the SA protocol and the
> system blow up for some structures:
>
> NSTEP = 1800 TIME(PS) = 10.900 TEMP(K) = 735.86 PRESS
> NSTEP = 2000 TIME(PS) = 11.000 TEMP(K) = 10363.98 PRESS
> NSTEP = 2200 TIME(PS) = 11.100 TEMP(K) = 7826.16 PRESS
You need to have enough temperature control to prevent getting temperatures of
10,000 degrees. I'd recommend trying ntt=3 for this. Note that there is no
real equivalent of tautp then: you have to just change the target temperature
as a function of time to get the temperature profile you want.
(ntt=3 offers better temperature regulation, especially for smallish systems,
or systems without explicit solvent. Note that it is quite common to have to
experiment a bit with a simulated annealing input to get a temperature vs.
time profile that is effective.)
You may also have a problem with the COOH group, but try the above first.
...good luck...dac
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Received on Wed Nov 07 2012 - 07:00:04 PST
