[ase-users] [gpaw-users] Embedded GW calculations with ASE and GPAW

[Asmus Ougaard Dohn]

Dear Marc Barbry,

Thanks for the interest in the ASE QM/MM functionality. I realise that the implementation is lacking some documentation and more tutorials, apologies. In any case, staying within ASE only for MM subsystems, my colleague Gianluca has recently implemented a force field for acetonitrile, which also works in QM/MM (see e.g. https://wiki.fysik.dtu.dk/ase/dev/tutorials/acn_equil/acn_equil.html). However, it is also possible to couple GPAW (and other QM calculators) to more general MM subsystems, which then just need an external MM code to handle energy and forces internally within the MM subsystem. I'm working with colleagues that achieve this using Amber (and it's ASE calculator interface), and they can model MM subsystems containing both water and a variety of smaller biomolecules, coupled to a QM subsystem.

I'd be happy to help with any issues there might be if you need to couple new MM codes. The ASE interface needs some specific methods to present the point charges to the QM calculator, and likewise, for new QM codes, you need to feed the point charges into their external potentials. I think, in a lot of cases, most of it is already there, in ASE.

Currently, we have no automated or tested way of coupling QM and MM over covalent bonds, and I don't really know anything about GW, sorry. I can see there's also now a force-mixing QM/MM calculator in ASE, I don't know anything about that one either.

Feel free to contact me directly, or continue through here, I'm not sure what the best practices for the mailing list are exactly.

Best,

Asmus




Asmus Ougaard Dohn

Research Assistant Professor

Science Institute, University of Iceland

Phone: +354 831 9337



________________________________
From: gpaw-users-bounces at listserv.fysik.dtu.dk <gpaw-users-bounces at listserv.fysik.dtu.dk> on behalf of marc barbry via gpaw-users <gpaw-users at listserv.fysik.dtu.dk>
Sent: Wednesday, May 29, 2019 3:05 PM
To: ase-users at listserv.fysik.dtu.dk; gpaw-users at listserv.fysik.dtu.dk
Subject: [gpaw-users] Embedded GW calculations with ASE and GPAW

Dear ASE and GPAW communities,

I am interested into calculating the energy level of organic molecules, taking into account the environment via QM/MM calculations. I went through the ASE tutorial on QM/MM method and the associated papers and it looks like what I would need. However, the ASE implementation seems to focus on water molecule. Is it possible to run QM/MM calculations for another environment than water? Where could I find some examples?

Furthermore, I would rather use GW to get the energy level and not only DFT. Is it possible to use the embedded method with the GW module of GPAW?

If you know other software that can perform embedded GW calculations I would be curious to learn about it. I know that the programs Votca and Fiesta provide such method, but they do not come with tutorials or are not open-source.

Thanks in advance,
Marc Barbry
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