[Wien] GaP NMR chemical shift question

[Jing-Han Chen]

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.

-- 
Jing-Han Chen
Graduate Student
Department of Physics
Texas A&M University
4242 TAMU
College Station TX  77843-4242
jhchen at tamu.edu <jhchen at tamu.edu> / http://people.physics.tamu.edu/jhchen/