[gmx-users] water flow

Justin Lemkul jalemkul at vt.edu
Tue Jun 12 19:38:32 CEST 2018

On 6/12/18 1:37 PM, Alex wrote:
> Hi Justin,
> Looking at acc-grps text in the manual, it's a bit unclear how a 
> constant flow rate would be achieved in this case. Is a constant force 
> in the amount of molecule mass, times the acceleration vector applied 
> to each molecule in the group, or is there actual acceleration 
> magically maintained?

I'm not familiar with the code, but it's what I know people have used to 
impose a constant force on a bulk solvent without having to use the pull 
code (which will throw errors).


> Thanks,
> Alex
> On 6/12/2018 8:24 AM, Justin Lemkul wrote:
>> On 6/11/18 7:38 PM, Alex wrote:
>>> Hi all,
>>> I'm trying to explore pressure-induced processes, i.e. externally 
>>> induced
>>> water flow across a porous membrane that spans the entire box in XY. 
>>> There
>>> are obvious choices:
>>> 1. Introduce the same type of a membrane without pores and make it a 
>>> piston
>>> with pull code, e.g. constant force or tiny constant velocity along Z.
>>> 2. Apply constant force pull directly to the entire solvent group.
>>> Any other ideas on osmosis-like processes? Has anyone tried any of the
>>> options above?
>> I would think the pull code would be more headache than it's worth in 
>> this case. I'd simply try inducing the flow with acc-grps.
>> -Justin


Justin A. Lemkul, Ph.D.
Assistant Professor
Virginia Tech Department of Biochemistry

303 Engel Hall
340 West Campus Dr.
Blacksburg, VA 24061

jalemkul at vt.edu | (540) 231-3129


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