[Wien] a question about geometry optimization on Ca_cmca

[zhs064]

Dear Wien2k users,

     I'm working on Ca_cmca (space group is 64) at high pressure. I got 
all cell constants
and atomic positions from the optimized values generated by the other
program. The initial structure file looks like:
**************************************************************
Title Ca         cmca
CXY                          1
MODE OF CALC=RELA
  8.435170  8.861303  8.446130 90.000000 90.000000 90.000000
ATOM  -1: X=0.00000000 Y=0.34493000 Z=0.19252000
          MULT= 4          ISPLIT=
      -1: X=0.00000000 Y=0.15507000 Z=0.69252000
      -1: X=0.00000000 Y=0.84493000 Z=0.30748000
      -1: X=0.00000000 Y=0.65507000 Z=0.80748000
Calcium    NPT=  781  R0=.000500000 RMT=             Z: 20.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
   0
***************************************************************
I wanna do the optimization on both cell constants and atomic positions 
with constant
volumes. The question is I found the optimized cell constants don't 
change and the atomic positions changed
very small (< 0.001), I think these results doesn't make sense. Anybody 
can tell me some ideas about them?
What I did is the following commands:
-- instgen_lapw
-- init_lapw  (I used PBE -6.0 Ry )
-- run_lapw (scf)
-- x optimize  (actually in this step, I chose "[3]  VARY C/A RATIO with 
CONSTANT VOLUME and B/A (orthorh lattice)"
   at -4,-2,0,2,4, then at each C/A variation I run "x optimize" again 
to get 5 B/A variations and renamed them, i.e. chose
   "[4]  VARY B/A RATIO with CONSTANT VOLUME and C/A (orthorh lattice)", 
finally I got 25 structure files)
-- I changed the script " optimize.job ", see below.
****************************************************
#!/bin/csh -f
 #   Modify this script according to your needs:
 #      Uncomment one of the lines ...
 #      Change run_lapw to runsp_lapw or use different convergence criterium
 #      Change save_lapw -d XXX
foreach i ( \
                                   Ca_cmca_1_5_boa___0.0_0   \
                                   Ca_cmca_1_5_boa___0.0_-4  \
                                   Ca_cmca_1_5_boa__-4.0_-4  \
                                   Ca_cmca_1_5_boa__-2.0_-4  \
                                   Ca_cmca_1_5_boa___2.0_-4  \
                                   Ca_cmca_1_5_boa___4.0_-4  \
                                   Ca_cmca_1_5_boa__-4.0_-2  \
                                   Ca_cmca_1_5_boa__-2.0_-2  \
                                   Ca_cmca_1_5_boa___0.0_-2  \
                                   Ca_cmca_1_5_boa___2.0_-2  \
                                   Ca_cmca_1_5_boa___4.0_-2  \
                                   Ca_cmca_1_5_boa__-4.0_0   \
                                   Ca_cmca_1_5_boa__-2.0_0   \
                                   Ca_cmca_1_5_boa___2.0_0   \
                                   Ca_cmca_1_5_boa___4.0_0   \
                                   Ca_cmca_1_5_boa__-4.0_2   \
                                   Ca_cmca_1_5_boa__-2.0_2   \
                                   Ca_cmca_1_5_boa___0.0_2   \
                                   Ca_cmca_1_5_boa___2.0_2   \
                                   Ca_cmca_1_5_boa___4.0_2   \
                                   Ca_cmca_1_5_boa__-4.0_4   \
                                   Ca_cmca_1_5_boa__-2.0_4   \
                                   Ca_cmca_1_5_boa___0.0_4   \
                                   Ca_cmca_1_5_boa___2.0_4   \
                                   Ca_cmca_1_5_boa___4.0_4   \
 )
     rm Ca_cmca_1_5.struct         # NFS-bug
     cp  $i.struct Ca_cmca_1_5.struct

 # Please uncomment and adapt any of the lines below according to your needs
 #    cp  $i.clmsum Ca_cmca_1_5.clmsum
     x dstart
 #    x dstart -c
 #    run_lapw -ec 0.0001 -in1new 3 -in1orig -renorm
 #    runsp_lapw -ec 0.0001
     min -I -j "run_lapw -p -fc 0.1 -i 200 -NI "
 #    run_lapw -ec 0.0001

     set stat = $status
     if ($stat) then
        echo "ERROR status in" $i
        exit 1
     endif
 #    save_lapw  $i
     save_lapw  -f -d /home/victor/wien2k_07/Ca_cmca_1_5/final $i
 end
**********************************************************

-- I also changed *.inM file, changed the force tolerance form 2 to 0.1 
mRy/a.u., I found the default value is
   too high.

-- finally I run the script "optimize.job"

After the calculations, I got the results as I stated before.

    Thank you very much!

Yours

Victor