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["Chun Li " <chun.li@mf.mpg.de>]

Dear all,

I am performing polarization calculations on ZnO surface model using
berry phase method. The system has been pre-relaxed using optcell=0 with
the thickness of the slab fixed. However, the polarization calculation
cannot converge. The residual energy is alternatively changed near about
10^-6. I have tried very small diemix (0.1, 0.05), but it doesn't help.
I also tried to use occopt=3 and tsmear=0.1 eV, but this is not allowed
in the polarization calculation. Hope those who have experiences can
give me some suggestions. Thanks a lot. We are using ABINIT4.3.4.

Best regards.

Chun Li

My input:

berryopt     -1      
rfdir        1 1 1

kptopt    3        
ngkpt    6 6 2

npsp  6                
znucl  8 30 8 9 29 30
                     
ntypat  4           
ntypalch   2       
                  
mixalch   
          0.50    0.50    0.0    0.0
          0.0     0.0     0.50   0.50
natom 12
typat 3 2 1 2 1 2 1 2 1 2 1 4

#Common data
    shiftk    0.0 0.0 0.5
   nshiftk    1
     acell    6.137678  6.137678 50.00000000
    diemac    12.0
    diemix    0.1
      ecut    50
      iscf    3
     nstep    115
    occopt    1
    angdeg    90 90 120
      xred
2.5223238036E-06 -2.5223238036E-06  4.5166780781E-03
6.6666782144E-01  3.3333217856E-01  2.3771347761E-02
6.6666783404E-01  3.3333216596E-01  9.8613542121E-02
2.2438912723E-06 -2.2438912723E-06  1.2280384925E-01
2.4278101458E-06 -2.4278101458E-06  1.9768470650E-01
6.6666791112E-01  3.3333208888E-01  2.2161495220E-01
6.6666783777E-01  3.3333216223E-01  2.9667323320E-01
2.3904195808E-06 -2.3904195808E-06  3.2031538720E-01
2.4345208968E-06 -2.4345208968E-06  3.9558813758E-01
6.6666790329E-01  3.3333209671E-01  4.1941862055E-01
6.6666747448E-01  3.3333252552E-01  4.9561991313E-01
2.7384543491E-06 -2.7384543491E-06  5.0835551120E-01
    toldfe    1.0d-12