[DFTB-Plus-User] NEMD MD with DFTB+

[Ankur Gupta]

Dear Dr. Goldman,

I am also quite interested in using Lammps functionalities with DFTB+
methods. I am especially interested in using GFN2-xTB methods through
Lammps. Also, it seems like one can install the LATTE package in Lammps to
use the DFTB methods; however, it probably doesn't have all the
Hamiltonians of DFTB+.

Best,
Ankur

On Wed, Jun 22, 2022 at 11:13 AM Goldman, Nir via DFTB-Plus-User <
dftb-plus-user at mailman.zfn.uni-bremen.de> wrote:

> Dear Ali,
>
> It's possible that you can get some of the MD functionality you mention
> through LAMMPS, if you haven't explored it already. We're currently working
> on a LAMMPS/DFTB+ interface that you might be able to use in the near
> future. Please feel free to reach out later in the summer to check on the
> status of all of that.
>
> Best,
>
> Nir
>
> --
> Nir Goldman
> Material Sciences Division, PLS
> Lawrence Livermore National Laboratory
> P.O. Box 808, L-285
> Livermore, CA 94551-0808
> Phone: (925) 422-3994
> https://people.llnl.gov/goldman14
>
> On 6/21/22, 5:39 AM, "DFTB-Plus-User on behalf of Bálint Aradi" <
> dftb-plus-user-bounces at mailman.zfn.uni-bremen.de on behalf of
> aradi at uni-bremen.de> wrote:
>
>     Dear Ali,
>
>     indeed, you can only apply isotropic pressure in DFTB+. And yes, the
>     non-equilibrium transport (via Greens functions) refers to the
>     electronic system (e.g. when you apply bias to your systems via
>     contacts), so this is not what you are looking for.
>
>     Unfortunately, I am definitely not an MD expert, so I am not sure,
> what
>     would be the right way to simulate you system.
>
>     Best regards,
>
>     Bálint
>
>     On 17.06.22 17:53, Alathea Davies wrote:
>     > Hello!
>     >
>     > I am hoping to conduct desalination simulations utilizing the MD
>     > functionality of DFTB+. I've been able to look at self diffusion
> between
>     > water, NaCl, and my membranes, and what I would like to do next is
> to
>     > apply a pressure difference in my simulation cell to simulate
>     > desalination. This would require setting the pressure at one end of
> my
>     > simulation cell different from the pressure at the other end. My
>     > intention is to apply pressure in the z-direction and periodic
> boundary
>     > conditions in both x- and y-. However, it doesn't seem that I would
> be
>     > able to do this with DFTB+. My understanding is that I can only
> define
>     > one external pressure around my entire periodic system, rather than
>     > defining different pressures at different boundaries. I've been
> reading
>     > through the manual extensively and searching online, but I can't
> come to
>     > a conclusive answer whether I'd be able to perform these simulations
> or
>     > if there is a work-around to do this with DFTB+. My two questions,
> then,
>     > are:
>     >
>     >  1. Does DFTB+ do non-equilibrium MD? Would other users have
> suggestions
>     >     how I could perform these calculations with DFTB+?
>     >
>     >  2. I understand that DFTB+ has the "Transport" calculations, but
> from
>     >     my understanding in the manual, these are more quantum mechanics
>     >     based transport (electrons, phonons, etc.) then mass transport.
> Am I
>     >     understanding this correctly?
>     >
>     > If there are any suggestions regarding how I could use DFTB+ MD
>     > functionality to conduct pressure-driven desalination simulations, I
>     > would be very grateful to hear them!
>     >
>     > Thank you so much for your help!
>     >
>     > ~ Alathea (Ali) Davies
>     >
>     >
>     > Graduate Research Assistant
>     > Computational Design Research Group
>     > University of Wyoming
>     > Department of Chemistry
>     > adavies2 at uwyo.edu
>     >
>     >
>     > _______________________________________________
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>     > DFTB-Plus-User at mailman.zfn.uni-bremen.de
>     >
> https://mailman.zfn.uni-bremen.de/cgi-bin/mailman/listinfo/dftb-plus-user
>
>
>     --
>     Dr. Bálint Aradi
>     Bremen Center for Computational Materials Science, University of Bremen
>     http://www.bccms.uni-bremen.de/cms/people/b-aradi/
>
>
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