[gmx-users] About Temperature coupling and Energy Transfer....

[Justin Lemkul]

On 11/20/12 5:42 PM, jhon michael espinosa duran wrote:
>
> Hi all.
>
> I am trying to simulate a protein initially at 0K
> in water at 310K. I couple the water to 310K with
> tc=0.5 and the Protein is decouple tc=-1.
>
> The idea is analyze how is the transfer of energy from the
> water to the protein.
>
> The interesting thing is that after 200ps the temperature of the
> water is constant (obviously) at 310K and the temperature of the protein
> goes up 628K!!!!!!
>
> I test the same system for different water temperatures 100K, 150K and 200K
> and the protein temperature always goes up 400K, 475K and 525K, respectively
>
> Can some one give an explanation?
>

It's because you have tau_t set to -1.  That tells mdrun not to control the 
temperature of the protein.  You've got warm solvent around a cold protein with 
an unregulated temperature, so the system is rapidly transferring heat into the 
protein and mdrun believes that's normal.

-Justin

-- 
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Justin A. Lemkul, Ph.D.
Research Scientist
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin

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