[Wien] GaP NMR chemical shift question

[Robert Laskowski]

Hi,

the two searings are not related. The metal option should only be used when you
have a real metal. GaP is semiconductor.


regards

Robert


On 28 April 2014 PM 10:19:50 Jing-Han Chen wrote:
> Hi, Robert
>
>   Thank you for your suggestion. I did use TETRA for GaP chemical
> shift calculation. The TEMP Fermi method in case.in2 does improve the
> result much better. However, we found that different values of TEMP
> with the same kbT size give different chemical shielding. Should we
> use the same value of TEMP in case.in2 as in metal option? If not, do
> you have any recommendation?
>
> 2014-04-21 1:29 GMT-05:00 Robert Laskowski <rolask at ihpc.a-star.edu.sg>:
> > Hi,
> >
> > the metal option works only with TEMP Fermi method in in2. Maybe you have TETRA, in this case Fermi level is shifted by 0.5 Ry, leading to wrong shielding.
> >
> > regards
> >
> > Robert
> >
> >
> >
> > On 18 April 2014 AM 11:07:27 Jing-Han Chen wrote:
> >> Dear WIEN2k users
> >>
> >>   We tried to use NMR package to verify GaP chemical shift. It has
> >> been known to be a semiconductor and is fcc with one Ga at (0,0,0)and
> >> one P at (1/4,1/4,1/4). We tried to use default and metal option to
> >> obtain Sigma-ISO and it gave us a surprising difference as the
> >> following(110000 k points)
> >>
> >> ==> default option <==
> >>
> >> :NMRTOT001  ATOM:       Ga   1  NMR(total/ppm) Sigma-ISO =   1353.09
> >>   Sigma_xx =   1353.09   Sigma_yy =   1353.09   Sigma_zz =   1353.09
> >> :NMRASY001  ATOM:       Ga   1  NMR(total/ppm) ANISO (delta-sigma) =
> >>    0.00     ASYM (eta) = 0.000     SPAN =      0.00     SKEW = 1.000
> >>
> >> :NMRTOT002  ATOM:        P   2  NMR(total/ppm) Sigma-ISO =    377.85
> >>   Sigma_xx =    377.85   Sigma_yy =    377.85   Sigma_zz =    377.85
> >> :NMRASY002  ATOM:        P   2  NMR(total/ppm) ANISO (delta-sigma) =
> >>    0.00     ASYM (eta) = 0.000     SPAN =      0.00     SKEW = 1.000
> >>
> >> ==> metal option <==
> >>
> >> :NMRTOT001  ATOM:       Ga   1  NMR(total/ppm) Sigma-ISO =   2704.12
> >>   Sigma_xx =   2704.12   Sigma_yy =   2704.12   Sigma_zz =   2704.12
> >> :NMRASY001  ATOM:       Ga   1  NMR(total/ppm) ANISO (delta-sigma) =
> >>    0.00     ASYM (eta) = 0.000     SPAN =      0.00     SKEW = 1.000
> >>
> >> :NMRTOT002  ATOM:        P   2  NMR(total/ppm) Sigma-ISO =   1082.72
> >>   Sigma_xx =   1082.72   Sigma_yy =   1082.72   Sigma_zz =   1082.72
> >> :NMRASY002  ATOM:        P   2  NMR(total/ppm) ANISO (delta-sigma) =
> >>    0.00     ASYM (eta) = 0.000     SPAN =      0.00     SKEW = 1.000
> >>
> >>   The difference is more than 1000ppm for Ga atom. We do this test
> >> since we want to understand how metal option works and the proper
> >> usage/parameters.
> >>
> >>   Any suggestion and comment are appreciated.
> >>
> >>
> > --
> > ==================================================
> > Dr. Robert Laskowski
> >
> > Senior Scientist, Materials Science & Engineering Department
> > Institute of High Performance Computing, A*STAR
> > 1 Fusionopolis Way, #16-16, Connexis, Singapore 138632
> > Tel(Off): +65. 64191493     Fax: +65. 64632536
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--
==================================================
Dr. Robert Laskowski

Senior Scientist, Materials Science & Engineering Department
Institute of High Performance Computing, A*STAR
1 Fusionopolis Way, #16-16, Connexis, Singapore 138632
Tel(Off): +65. 64191493     Fax: +65. 64632536
=================================================

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