[gpaw-users] some question about GPAW

[Eskil Varenius]

Hi!
I have a follow up question about spin-polarised vdW-DF. As far as I knew
the functionals vdW-DF 1 and 2 were only derived as spin-paired expressions.
I didn't know it was possible to do a spin-polarised calculation with these.
If it really is possible it is a great thing, but is there any article or
other source describing the "spin-polarisation" of vdW-DF?

Best regards,
Eskil Varenius, Master student at Chalmers, Sweden


2011/3/31 Jess Wellendorff Pedersen <jesswe at fysik.dtu.dk>

> Dear Wei-Bing,
>
> It appears that those particular GPAW wiki pages that you refer to have
> not been updated for some time. We apologize for this.
> The answers to your questions are simple:
>
> Wei-Bing Zhang wrote:
> >
> > Dear all
> >
> >
> >
> > I am trying to do some calculations using GPAW. But I found something
> > which I can’t understand fully.
> >
> > 1) On the webpage
> >
> https://wiki.fysik.dtu.dk/gpaw/tutorials/bandstructures/bandstructures.html
> > there is a sentence “One should note that as GPAW only works with
> > orthorhombic cells …..”.
> >
> > Does this means one has to use orthorhombic cells in the
> > calculations??  I use a non-orthorhombic cell for surface calculation
> > with GPAW, but the code didn’t complaint.  I want to know whether the
> > results including energy and geometry obtained using non-orthorhombic
> > cell in GPAW is valid or not???
> >
> GPAW natturally handles non-orthorhombic unit cells, and total energy as
> well as forces are completely valid.
> >
> > 2) On the webpage
> >
> https://wiki.fysik.dtu.dk/gpaw/documentation/xc/vdw.html#doing-a-van-der-waals-calculation
> >
> >
> > I found the “vdw = FFTVDWFunctional(nspins=1, verbose=True)”. It seems
> > that there is a keywords “nspin”, which should control spin polarized
> > or spin paired calculations. However, in the newer version GPAW, I
> > can’t find a keyword relate to spin polarized calculations. I want to
> > know whether the new version off vdW xc can treat the spin polarized
> > calculations or not??
> >
> The GPAW exchange-correlation library has been rearranged such that the
> vdW-DF type functionals (vdW-DF and vdW-DF2) are used on the same
> footing as e.g. LDA and GGA xc-functionals. This means that you simple
> do " xc = 'vdW-DF' " or " xc = 'vdW-DF2' " in order to use these to
> functionals. Spinpolarization is handled automatically "behind the
> scenes" or, if the ASE Atoms object has no magnetic moments but you for
> whatever reason still wants GPAW to do a spinpolarized calculation, you
> enforce this with "spinpol=True" in the GPAW object.
> Example:
> sys = Atoms(.......)
> calc = GPAW(xc='vdW-DF', txt='out.txt',spinpol=True)
> sys.set_calculator(calc)
>
> cheers,
> Jess Wellendorff
> >
> >
> >
> > Thanks and Best Wishes
> >
> >
> >
> > Wei-Bing Zhang
> >
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > gpaw-users mailing list
> > gpaw-users at listserv.fysik.dtu.dk
> > https://listserv.fysik.dtu.dk/mailman/listinfo/gpaw-users
>
> --
> Jess Wellendorff Pedersen
>
> ph.d student
> Center for Atomic-scale Materials Design (CAMD)
> Department of Physics
> Technical University of Denmark (DTU)
>
> _______________________________________________
> gpaw-users mailing list
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