[Wien] GaP NMR chemical shift question

[Robert Laskowski]

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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