[gmx-users] Re: RE: heat appears

[Anton Feenstra]

Spiwok Vojtech wrote:
>>I use the twin-range cutoff 0.8/1.2 and the temperature of the system
>>consisting of 500 H2O increased up to 310K while the reference temperature
>>is 300K.
> 
> 
> Use a single cut-off of 1.2 (or more) and the fever will be cured !

That doesn't seem like a good solution. If you simulate only water (nothing
in the water, like protein, ions or anything), you should be very close to
your ref_t.

What time constant do you have for temp-coupling (tau_t)?
What do you have for nstlist (neighborlist update frequency)?

Instead of going to single cut-off I'd suggest using PME for the long-range
electrostatics. Check the manual and/or mail archives how to do it.

> It was just guess. I don't know any sophisticated explanation.

The potential is discontinuous at the cut-off. This generates artificial
forces that accelerate your atoms, hence an increase in temperature.


-- 
Groetjes,

Anton
  _____________ _______________________________________________________
|             |                                                       |
|  _   _  ___,| K. Anton Feenstra                                     |
| / \ / \'| | | Dept. of Pharmacochem. - Vrije Universiteit Amsterdam |
|(   |   )| | | De Boelelaan 1083 - 1081 HV Amsterdam - Netherlands   |
| \_/ \_/ | | | Tel: +31 20 44 47608 - Fax: +31 20 44 47610           |
|             | Feenstra at chem.vu.nl - www.chem.vu.nl/~feenstra/       |
|             | "If You See Me Getting High, Knock Me Down"           |
|             | (Red Hot Chili Peppers)                               |
|_____________|_______________________________________________________|