Re: graphene sheet as a rigid piston

From: Hemanth Haridas (hemanth.h_at_iitgn.ac.in)
Date: Fri Apr 30 2021 - 05:28:47 CDT

Shivam,

I had some luck with using the SMD module to get graphene working as a
piston. The trick is to tag one graphene layer as moving (SMD active), and
to restrain the layer containing the nanopore with a very high harmonic
restraint.

Hope this helps,

Regards
Hemanth

On Wed, Apr 28, 2021 at 11:13 PM SHIVAM TIWARI <t.shivam_at_iitg.ac.in> wrote:

> Dear all,
> I want to simulate reverse osmosis process on a box of water and ions
> across a membrane, for which, I am applying a transmembrane pressure on the
> water box through a graphene sheet (as a piston). I am using tclforces to
> achieve this, the script I am using is as follows:
>
> tclForces on
>
> tclForcesScript {
> set linaccel1 {0.0 0.0 -0.0006449914635}
> set linaccel2 {0.0 0.0 0.0006449914635}
>
>
> set watIdList1 {}
> set watIdList2 {}
>
>
>
> for {set i 1} {$i <= 5520} {incr i} {
> lappend watIdList1 $i
> addatom $i
> }
> for {set i 229378} {$i <= 234897} {incr i} {
> lappend watIdList2 $i
> addatom $i
> }
>
> But the problem with this is that the graphene sheet behaves as a graphene
> sheet and not as a rigid piston, that is, the graphene sheet gets deformed
> (curled up) as soon as the pressure is applied. Although, the water does
> get pushed, but I suspect that the pressure applied in this case is much
> lesser than the desired, since most of the force applied on the graphene
> sheet must be getting wasted on the deformation of the graphene sheet. So
> how can I achieve a rigid graphene piston?
>
> regards
> shivam
>

-- 
*Hemanth H 18310019*
Research Scholar
IIT Gandhinagar

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