[Wien] re : Supercells - what is the right procedure to create an acceptable one?

[George Amolo]

Dear Wien2k users,

I am a fairly new user of the Wien2k code trying out some calculations of
dopant impurities in a diamond lattice supercell. The users forum has been
of immense help to me. I have followed with interest suggestions of Steven
Homolya (21st - 23rd October 2004) on how to fix hand-made struct files
and hence modify them to supercells. The last email, 23rd October, has a
caution from Jorrisen Kevin about the CXZ-bug if one accepts all the
output from sgroup. Would someone out there kindly outline in simple terms
what should be done.

I have started out with (despite Stefan's caution to Yaron and Angelica of
18th Jul 2003 not to give a spacegroup but rather start from a
P-structfile. This is because that route had even more problems)

diamond
F   LATTICE,NONEQUIV. ATOMS  1227_Fd-3m
MODE OF CALC=RELA unit=bohr
  6.740660  6.740660  6.740660 90.000000 90.000000 90.000000
ATOM   1: X=0.12500000 Y=0.12500000 Z=0.12500000
          MULT= 2          ISPLIT= 2
       1: X=0.87500000 Y=0.87500000 Z=0.87500000
C C1       NPT=  781  R0=0.00010000 RMT=    1.4500   Z:  6.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000

and went ahead to use the 'supercell' command online. Several warnings
appeared. I went ahead and accepted the suggested changes by updating them
to the case.struct file and then through the process of intialization of the
struct file which is now essentially that of a supercell. Note that a
nitrogen atoms was inserted into the supercell. The struct file before
running 'mini' is

Title
R                            4 166 R-3m
             RELA
  9.532733  9.532733 23.350331 90.000000 90.000000120.000000
ATOM  -1: X=0.31278464 Y=0.31278464 Z=0.81217227
          MULT= 6          ISPLIT= 8
      -1: X=0.81217227 Y=0.31278464 Z=0.31278464
      -1: X=0.31278464 Y=0.81217227 Z=0.31278464
      -1: X=0.68721536 Y=0.68721536 Z=0.18782773
      -1: X=0.68721536 Y=0.18782773 Z=0.68721536
      -1: X=0.18782773 Y=0.68721536 Z=0.68721536
C 1        NPT=  781  R0=.000100000 RMT=   1.45000   Z:   6.00000
LOCAL ROT MATRIX:    0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
                     1.0000000 0.0000000 0.0000000
ATOM  -2: X=0.81302209 Y=0.81302209 Z=0.30880538
          MULT= 6          ISPLIT= 8
      -2: X=0.30880538 Y=0.81302209 Z=0.81302209
      -2: X=0.81302209 Y=0.30880538 Z=0.81302209
      -2: X=0.18697791 Y=0.18697791 Z=0.69119462
      -2: X=0.18697791 Y=0.69119462 Z=0.18697791
      -2: X=0.69119462 Y=0.18697791 Z=0.18697791
C 2        NPT=  781  R0=.000100000 RMT=   1.45000   Z:   6.00000
LOCAL ROT MATRIX:    0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
                     1.0000000 0.0000000 0.0000000
ATOM  -3: X=0.31301112 Y=0.31301112 Z=0.31301112
          MULT= 2          ISPLIT= 4
      -3: X=0.68698888 Y=0.68698888 Z=0.68698888
N 1        NPT=  781  R0=.000100000 RMT=   1.45000   Z:   7.00000
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
ATOM  -4: X=0.81511300 Y=0.81511300 Z=0.81511300
          MULT= 2          ISPLIT= 4
      -4: X=0.18488700 Y=0.18488700 Z=0.18488700
C 3        NPT=  781  R0=.000100000 RMT=   1.45000   Z:   6.00000
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
  12      NUMBER OF SYMMETRY OPERATIONS
 1 0 00.00000000
 0 1 00.00000000
 0 0 10.00000000
   1
 0 0 10.00000000
 1 0 00.00000000
 0 1 00.00000000
   2
 0 1 00.00000000
 0 0 10.00000000
 1 0 00.00000000
   3
 0-1 00.00000000
-1 0 00.00000000
 0 0-10.00000000
   4
-1 0 00.00000000
 0 0-10.00000000
 0-1 00.00000000
   5
 0 0-10.00000000
 0-1 00.00000000
-1 0 00.00000000
   6
-1 0 00.00000000
 0-1 00.00000000
 0 0-10.00000000
   7
 0 0-10.00000000
-1 0 00.00000000
 0-1 00.00000000
   8
 0-1 00.00000000
 0 0-10.00000000
-1 0 00.00000000
   9
 0 1 00.00000000
 1 0 00.00000000
 0 0 10.00000000
  10
 1 0 00.00000000
 0 0 10.00000000
 0 1 00.00000000
  11
 0 0 10.00000000
 0 1 00.00000000
 1 0 00.00000000
  12

I invoked  min_lapw -j 'run_lapw -I -fc 1.0 -i 50' for a trial minimization
and run the following 'mini' error after more than an hour

 'NN' - overlapping spheres
 'NN' - RMT( 1)=1.45000 AND RMT( 2)=1.45000
 'NN' - SUMS TO 2.90000 GT NNN-DIST= 2.89817

Please advice me on this rather long story. Thank you.

george Amolo