The ABINIT Users Mailing List ( CLOSED )

[Nicola Marzari <marzari@mit.edu>]

Dear James,


LDA/GGA work functions in Mg(0001) have been studied before, reporting
e.g. 3.88 (LDA), 3.76 (GGA) vs 3.84 eV (expt) (Kiejna 2001 JPCM), so
LDA/GGA seem to be doing a good job.

                                nicola


> > ----- Oryginalna wiadomo?? -----
> > Od: James Johns <jej7x@xenon.cchem.berkeley.edu>
> > Data: Niedziela, Kwiecie? 22, 2007 6:49 am
> > Temat: [abinit-forum] Mg workfunction
> > Do: forum@abinit.org
> >
> > > Ok, so I'm going partially off of the tutorials here, but I'm
> > > attempting
> > > to approximate the workfunction of Magnesium(0001) surfaces.  I've
> > > attatched a sample input file.  My problem is that despite all
> > > attempts to
> > > better optimize the convergence critea based on nband, ecut, the
> > > kpt grid,
> > > or anything, it's underestimating the workfunction by roughly a
> > > factor of
> > > two.  I'm using the fermi level energy level from a 10 atom slab
> > > calculation as the workfunction.  Is there something wrong with
> > > this?
> > > When I do this for the Ag(111) surface, my estimation is roughly
> > > 100-200meV higher than the experimental version.  The fact that
> > > it's only
> > > slightly more ( and seems to converge based on typical paramters
> > > such as
> > > size of vaccuum spacing etc), while on Mg it is severely less
> > > makes me
> > > think that it's not something inherent in the LDA (or GGA)
> > > approximation.
> > > Does anyone have any thoughts, or alterations to the input file to
> > > correct
> > > for something I'm doing stupidly?
> > > Thanks a lot,
> > > --James Johns
> > > UC Berkeley
> > > Charles Harris group member


--
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Prof Nicola Marzari   Department of Materials Science and Engineering
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