[gmx-users] adding an external body force

[Michele Pellegrino]

Justin,

thank you very much for the clarification.
I believe the documentation should report 'add', instead of 'impose' (otherwise it may be confusing).

Regards,
Michele 
________________________________________
From: gromacs.org_gmx-users-bounces at maillist.sys.kth.se <gromacs.org_gmx-users-bounces at maillist.sys.kth.se> on behalf of Justin Lemkul <jalemkul at vt.edu>
Sent: 06 February 2020 14:47
To: gmx-users at gromacs.org
Subject: Re: [gmx-users] adding an external body force

On 2/6/20 4:58 AM, Michele Pellegrino wrote:
> Hi,
>
>
> I was wondering how to apply an external forcing term to one group; looking at the 2020 documentation I found:
>
>
> "
>
> accelerate group
> On each atom in an "accelerate group" an acceleration a_g is imposed. This is equivalent to an external force.
>
> "
>
>
> However I would argue it is not equivalent at all: the contibution of an external body force would add an acceleration term, not impose it, right?
>
> To make a more concrete example, what if I want to simulate gravity by setting 'accelerate' to some value? Would I obtain free-falling or would gravity be added on top of the force field from atomic intercations?

The use of acceleration groups simply adds an acceleration to the one
that arises from the forces in the simulation and acts in the update step.

-Justin

--
==================================================

Justin A. Lemkul, Ph.D.
Assistant Professor
Office: 301 Fralin Hall
Lab: 303 Engel Hall

Virginia Tech Department of Biochemistry
340 West Campus Dr.
Blacksburg, VA 24061

jalemkul at vt.edu | (540) 231-3129
http://www.thelemkullab.com

==================================================

--
Gromacs Users mailing list

* Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting!

* Can't post? Read http://www.gromacs.org/Support/Mailing_Lists

* For (un)subscribe requests visit
https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to gmx-users-request at gromacs.org.