[gmx-users] NVE+NVE: Two groups: one with Tcouple while the other one not

2015-09-10 Thread Guiyuan Mo
Hi, 


I am modelling a box with two groups of molecule: N2 and C12H26. 
1. Initially, NVT was used for both: 

; Temperature coupling is on 
Tcoupl = nose-hoover 
tau_t = 1.0 1.0 
tc-grps = N2 nC12 
ref_t = 450 300 


2. Then I turned off the Tcoupl for nC12 (by setting tau_t = -1): 

; Temperature coupling is on 
Tcoupl = nose-hoover 
tau_t = 1.0 -1 
tc-grps = N2 nC12 
ref_t = 450 300 


What I expected was that nC12 was heated up by N2. However the system 
temperature would go much higher than 450K... We know this is not true. 


Does anyone can help me? Is there something wrong or needed to take care when 
using tau_t = -1? Thanks. 


Best, 
Mo 
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Re: [gmx-users] NVE+NVE: Two groups: one with Tcouple while the other one not

2015-09-10 Thread Vitaly V. Chaban
The reason is the slow energy exchange between the gas and the solid.



On Thu, Sep 10, 2015 at 9:47 PM, Guiyuan Mo <g...@purdue.edu> wrote:

> Okay. Thank you VV.
>
> But the simulation result show that the system temperature would go up to
> 1000K after I turned off the Tcoupl for nC12 (by setting tau_t = -1). What
> would be reasons?
>
> --
> *From: *"Vitaly V. Chaban" <vvcha...@gmail.com>
> *To: *"gmx-users" <gmx-us...@gromacs.org>
> *Sent: *Thursday, September 10, 2015 8:37:52 PM
> *Subject: *Re: [gmx-users] NVE+NVE: Two groups: one with Tcouple while
> the other one not
>
> Sure.
>
> N2 heats the large moleculle which dissipates heat much more slowly and
> does not have a thermostat to help it.
>
>
>
>
> On Thu, Sep 10, 2015 at 9:09 PM, Guiyuan Mo <g...@purdue.edu> wrote:
>
> > Hi,
> >
> >
> > I am modelling a box with two groups of molecule: N2 and C12H26.
> > 1. Initially, NVT was used for both:
> >
> > ; Temperature coupling is on
> > Tcoupl = nose-hoover
> > tau_t = 1.0 1.0
> > tc-grps = N2 nC12
> > ref_t = 450 300
> >
> >
> > 2. Then I turned off the Tcoupl for nC12 (by setting tau_t = -1):
> >
> > ; Temperature coupling is on
> > Tcoupl = nose-hoover
> > tau_t = 1.0 -1
> > tc-grps = N2 nC12
> > ref_t = 450 300
> >
> >
> > What I expected was that nC12 was heated up by N2. However the system
> > temperature would go much higher than 450K... We know this is not true.
> >
> >
> > Does anyone can help me? Is there something wrong or needed to take care
> > when using tau_t = -1? Thanks.
> >
> >
> > Best,
> > Mo
> > --
> > Gromacs Users mailing list
> >
> > * Please search the archive at
> > http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before
> > posting!
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> > send a mail to gmx-users-requ...@gromacs.org.
> >
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> Gromacs Users mailing list
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> posting!
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