[Wien] zigzag potential (remaining questions)
Stefaan Cottenier
Stefaan.Cottenier at UGent.be
Fri Jan 5 17:58:13 CET 2018
Curiously, the nonselfconsistent test gives 0.994 V/Ang instead of the intended 0.500 V/Ang (too close to a factor two to be a coincidence?).
The list refused this mail with pictures included, I can send those privately if needed (onedimensional potential plot, selfconsistently and non-selfconsistently).
Stefaan
> -----Oorspronkelijk bericht-----
> Van: Wien [mailto:wien-bounces at zeus.theochem.tuwien.ac.at] Namens
> Peter Blaha
> Verzonden: vrijdag 5 januari 2018 16:55
> Aan: wien at zeus.theochem.tuwien.ac.at<mailto:wien at zeus.theochem.tuwien.ac.at>
> Onderwerp: Re: [Wien] zigzag potential (remaining questions)
>
> Hallo Stefan,
>
> Thanks for the suggestions, I'll take them.
>
> Please test the plotted potential again, but WITHOUT selfconsistency !!!
>
> i.e.
> Start from a converged calculation WITHOUT field.
> Put the field into case.in0 and R2V
> x lapw0
> cp the potential to case.clmvalup
> x lapw5 -up (-c not needed)
>
> I'd expect there is a counteracting field developing during scf, which reduces
> the applied field.
>
> On 01/05/2018 03:53 PM, Stefaan Cottenier wrote:
> > Hello Peter,
> >
> >> I can only recommend to put R2V in case.in0 and plot the resulting
> >> potentials with a field. (Best is a 1D plot along z, preferentially
> >> not through any atoms.) You should clearly see where the kinks are,
> >> and also how large delta-V / delta-l really is (plot in Ry units in in5).
> >>
> >> In that way you can verify if the statement in the UG is correct or not.
> >
> > I did that, for the case.struct pasted at the end, in the following way:
> >
> > runsp -so
> > cp case.vtotal case.clmvalup
> > x lapw5 -c -up
> >
> > where this was the content of case.in0 (R2V and electric field):
> >
> > TOT XC_PBE (XC_LDA,XC_PBESOL,XC_WC,XC_MBJ,XC_REVTPSS)
> > R2V IFFT (R2V)
> > 30 30 360 2.00 1 min IFFT-parameters, enhancement factor, iprint
> > 30 1.266176 1.
> >
> > and where this was the content of case.in5c (a single line through the
> vacuum and through the slab, in a region as far as possible from the nuclei):
> >
> > 0.50 0.00 0.00 1
> > 0.50 0.00 1.00 1
> > 0.50 0.00 0.00 1
> > 3 3 3
> > 100 1
> > RHO
> > ATU VAL NODEBUG
> >
> > The result is a graph where I do see the kink halfway the unit cell.
> > That confirms that the default zigzag potential is as shown in Fig. 6
> > of http://dx.doi.org/10.1103/PhysRevB.63.165205 . [while writing this,
> > Gavin's analysis appeared on the list, which confirms this]
> >
> > The value of the field is not fully clear, however. In the vacuum region of
> the unit cell, there is a section of length 16.4349 bohr where the potential is
> nicely linear. The potential change over that interval is 0.270806 Ry. The
> absolute value of the constant electric field in that vacuum region is
> therefore 0.270806/16.4349 = 0.016477 Ry/bohr. That's 0.423 V/Ang.
> >
> > However, for the EFIELD value of 1.266176 (see case.in0 above) and c
> lattice parameter of 65.082193 bohr, the specified electric field should be
> according to the usersguide 1.266176/65.082193 = 0.019455 Ry/bohr = 0.500
> V/Ang.
> >
> > That means there is no issue with a possible factor 2 (the statement in the
> usersguide is correct), but now I'm puzzled about the difference between
> 0.423 and 0.500 V/Ang. That looks to be too large to be noise...?
> >
> >> PS: I'll take up any "explicit" suggestion for the UG. (but not just
> >> "please improve it").
> >
> > Point taken, yet I was in need of the hints hereabove before I could make
> sense of it. These are the changes I would now propose:
> >
> > * I suggest to remove the line 317 in eramps.f that Gavin mentions, in order
> to print the applied potential in case.output0 by default. It will not hinder
> anybody as this option is rarely used, and for those using it it will at least tell
> unambiguously which applied potential is present.
> >
> > * This is a more explicit text for the usersguide, that would have prevented
> most of my doubts:
> >
> > =======
> > IFIELD: number of Fourier coefficients to model the zig-zag potential, also
> known as the 'analytic triangular ramp' (mode=0, default). Typically use
> IFIELD=30 (the maximal value is IEFIELD=999, but you should stay way below
> that). This zig-zag potential reaches maxima at z=0 and z=1, and a minimum
> at z=0.5 (see fig. 6 of [Stahn et al., 2001]). Using IFIELD=-999 (with a random
> value for EFIELD) lists in case.output0 the other available modes (forms) of
> electric fields. You can select mode n by specifying IFIELD=n*1000 (e.g.
> IFIELD=4000 gives you mode 4). The mode that is being used, is printed at the
> top of case.output0.
> >
> > EFIELD: value (amplitude) of the electric field. The electric field (in Ry/bohr)
> corresponds to EFIELD/c, where c is your c lattice parameter. In order to have
> the electric field in Volt/Angstrom, multiply EFIELD/c by 13.6/0.529177.
> >
> > WFIELD: optional value for lambda (see output of IFIELD=-999).
> > ==========
> >
> > Best regards,
> > Stefaan
> >
> >
> > blebleble s-o calc. M|| 0.00 0.00 1.00
> > P 7 99 P
> > RELA
> > 5.423516 5.423516 65.082193 90.000000 90.000000 90.000000 ATOM
> > -1: X=0.00000000 Y=0.00000000 Z=0.12500000
> > MULT= 1 ISPLIT=-2
> > Fe1 NPT= 781 R0=.000050000 RMT= 2.22000 Z: 26.00000
> > LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
> > 0.0000000 1.0000000 0.0000000
> > 0.0000000 0.0000000 1.0000000 ATOM -2:
> > X=0.00000000 Y=0.00000000 Z=0.37500000
> > MULT= 1 ISPLIT=-2
> > Fe2 NPT= 781 R0=.000050000 RMT= 2.22000 Z: 26.00000
> > LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
> > 0.0000000 1.0000000 0.0000000
> > 0.0000000 0.0000000 1.0000000 ATOM -3:
> > X=0.00000000 Y=0.00000000 Z=0.20833333
> > MULT= 1 ISPLIT=-2
> > Fe3 NPT= 781 R0=.000050000 RMT= 2.22000 Z: 26.00000
> > LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
> > 0.0000000 1.0000000 0.0000000
> > 0.0000000 0.0000000 1.0000000 ATOM -4:
> > X=0.00000000 Y=0.00000000 Z=0.29166667
> > MULT= 1 ISPLIT=-2
> > Fe4 NPT= 781 R0=.000050000 RMT= 2.22000 Z: 26.00000
> > LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
> > 0.0000000 1.0000000 0.0000000
> > 0.0000000 0.0000000 1.0000000 ATOM -5:
> > X=0.50000000 Y=0.50000000 Z=0.16666667
> > MULT= 1 ISPLIT=-2
> > Fe5 NPT= 781 R0=.000050000 RMT= 2.22000 Z: 26.00000
> > LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
> > 0.0000000 1.0000000 0.0000000
> > 0.0000000 0.0000000 1.0000000 ATOM -6:
> > X=0.50000000 Y=0.50000000 Z=0.33333333
> > MULT= 1 ISPLIT=-2
> > Fe6 NPT= 781 R0=.000050000 RMT= 2.22000 Z: 26.00000
> > LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
> > 0.0000000 1.0000000 0.0000000
> > 0.0000000 0.0000000 1.0000000 ATOM -7:
> > X=0.50000000 Y=0.50000000 Z=0.25000000
> > MULT= 1 ISPLIT=-2
> > Fe7 NPT= 781 R0=.000050000 RMT= 2.22000 Z: 26.00000
> > LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
> > 0.0000000 1.0000000 0.0000000
> > 0.0000000 0.0000000 1.0000000
> > 8 NUMBER OF SYMMETRY OPERATIONS
> >
> >
> > _______________________________________________
> > Wien mailing list
> > Wien at zeus.theochem.tuwien.ac.at<mailto:Wien at zeus.theochem.tuwien.ac.at>
> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> > SEARCH the MAILING-LIST at:
> > http://www.mail-<http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html>
> archive.com/wien at zeus.theochem.tuwien.ac.at/index.html<http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html>
> >
>
> --
>
> P.Blaha
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
> Email: blaha at theochem.tuwien.ac.at<mailto:blaha at theochem.tuwien.ac.at> WIEN2k: http://www.wien2k.at
> WWW: http://www.imc.tuwien.ac.at/TC_Blaha
> --------------------------------------------------------------------------
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at<mailto:Wien at zeus.theochem.tuwien.ac.at>
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at: http://www.mail-<http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html>
> archive.com/wien at zeus.theochem.tuwien.ac.at/index.html<http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20180105/b723f708/attachment.html>
More information about the Wien
mailing list