[gmx-users] The difference about NPT and NVT ensemble.

[Justin A. Lemkul]

fufengliu wrote:
> Hello, everyone,
> 
> I have some questions about ensemble. Would you please tell me about NPT 
> or NVT ensemble? What difference about them? And how to define in the 
> molecular dynamics mdp file? What ensemble does the below parameters 
> extracted from my mdp file?
> 

NPT = constant Number of molecules, Pressure, Temperature
NVT = constant Number of molecules, Volume, Temperature

If you are blindly writing .mdp parameters without knowing what you are doing, 
you had better re-think your approach.  Your comments in the file will tell you 
what you are doing.  Sounds like some textbook reading (regarding ensembles) 
would be useful, as well as a thorough read of the Gromacs manual to learn what 
the options are doing.

-Justin

> 
> ; Berendsen temperature coupling is on
> 
> Tcoupl              =  berendsen
> 
> tau_t               =  0.1         0.1
> 
> tc-grps           =  protein  non-protein
> 
> ref_t               =  300         300
> 
> ; Pressure coupling is on
> 
> Pcoupl              =  berendsen
> 
> Pcoupltype          = isotropic
> 
> tau_p               =  0.5
> 
> compressibility     =  4.5e-5
> 
> ref_p               =  1.0
> 
> 
> Thank you for your kind consideration of these questions.
> 
> 
> Sincerely,
> 
> 
> Fufeng Liu
> 
> 
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> 
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-- 
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Justin A. Lemkul
Graduate Research Assistant
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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