[Pw_forum] Relaxation with Spin-Orbit Coupling

Julen Ibanez Azpiroz julen.azpiroz at gmail.com
Tue Jul 13 11:59:03 CEST 2010


Hello, thanks for answering,

This is the input:



&control
  calculation='relax',
  dt=10.D0,
  tstress=.true.
  tprnfor=.true.
  verbosity='high',
  restart_mode='from_scratch',
  prefix='si_dt_scalar',
  pseudo_dir='./',
  outdir='/lscratch/azpiroz/relax_sc_pos/'
  forc_conv_thr=1.0D-4 ,
/
&system
  ibrav=12,
  celldm(1)= 7.30868, celldm(2)= 1, celldm(3)= 17.044354, celldm(4)= 0.5,
  nat=26,
  ntyp=2,
  ecutwfc =45,
  noncolin=.true.
  lspinorb=.true.
  occupations='smearing',
  smearing='methfessel-paxton',
  degauss=0.05d0
/
&electrons
  conv_thr=1.0e-6,
  mixing_beta=0.3d0
/
&IONS
 ion_dynamics = "damp",
 pot_extrapolation = "second_order",
 wfc_extrapolation = "second_order",
/
ATOMIC_SPECIES
Si 28.086 Si.rel-pbe-rrkj.UPF
Tl 204.383 Tl.6d_relat_rrkj_nc.UPF
ATOMIC_POSITIONS
Tl        0.000000000  -0.000000003  -5.314678016   0   0   1
Si       -0.500000000  -0.288675141  -4.796768286   0   0   1
Si       -0.500000000  -0.288675106  -4.190720851   0   0   1
Si        0.000000000   0.000000030  -3.983120071   0   0   1
Si        0.000000000   0.000000005  -3.369968660   0   0   1
Si        0.500000000   0.288675142  -3.165727013   0   0   1
Si        0.500000000   0.288675167  -2.553252172   0   0   1
Si       -0.500000000  -0.288675100  -2.348809321   0   0   1
Si       -0.500000000  -0.288675113  -1.736391979   0   0   1
Si        0.000000000   0.000000020  -1.531756523   0   0   1
Si        0.000000000   0.000000029  -0.919281369   0   0   1
Si        0.500000000   0.288675161  -0.714766469   0   0   1
Si        0.500000000   0.288675135  -0.102266533   0   0   1
Si       -0.500000000  -0.288675135   0.102266533   0   0   1
Si       -0.500000000  -0.288675161   0.714766469   0   0   1
Si        0.000000000  -0.000000029   0.919281369   0   0   1
Si        0.000000000  -0.000000020   1.531756523   0   0   1
Si        0.500000000   0.288675113   1.736391979   0   0   1
Si        0.500000000   0.288675100   2.348809321   0   0   1
Si       -0.500000000  -0.288675167   2.553252172   0   0   1
Si       -0.500000000  -0.288675142   3.165727013   0   0   1
Si        0.000000000  -0.000000005   3.369968660   0   0   1
Si        0.000000000  -0.000000030   3.983120071   0   0   1
Si        0.500000000   0.288675106   4.190720851   0   0   1
Si        0.500000000   0.288675141   4.796768286   0   0   1
Tl        0.000000000   0.000000003   5.314678016   0   0   1
K_POINTS {automatic}
16 16 1 0 0 0



This is the structure A, the output gives energy -207.10202515 Ry, but the
forces in the ouput are:


!    total energy              =    -207.10202515 Ry
     Harris-Foulkes estimate   =    -207.10202560 Ry
     estimated scf accuracy    <       0.00000040 Ry

     convergence has been achieved in  19 iterations

     Forces acting on atoms (Ry/au):


     atom   1 type  2   force =     0.00000000    0.00000000   -0.01317569
     atom   2 type  1   force =     0.00000000    0.00000000   -0.00615334
     atom   3 type  1   force =     0.00000000    0.00000000    0.00105593
     atom   4 type  1   force =     0.00000000   -0.00000001   -0.00059280
     atom   5 type  1   force =     0.00000000    0.00000001   -0.00026662
     atom   6 type  1   force =     0.00000000    0.00000000    0.00008699
     atom   7 type  1   force =     0.00000000    0.00000000   -0.00000917
     atom   8 type  1   force =     0.00000000    0.00000000   -0.00002700
     atom   9 type  1   force =     0.00000000    0.00000000    0.00015023
     atom  10 type  1   force =     0.00000000    0.00000000   -0.00013355
     atom  11 type  1   force =     0.00000000    0.00000000    0.00004536
     atom  12 type  1   force =     0.00000000    0.00000000   -0.00005356
     atom  13 type  1   force =     0.00000000    0.00000000    0.00008346
     atom  14 type  1   force =     0.00000000    0.00000000   -0.00008346
     atom  15 type  1   force =     0.00000000    0.00000000    0.00005356
     atom  16 type  1   force =     0.00000000    0.00000000   -0.00004536
     atom  17 type  1   force =     0.00000000    0.00000000    0.00013355
     atom  18 type  1   force =     0.00000000    0.00000000   -0.00015023
     atom  19 type  1   force =     0.00000000    0.00000000    0.00002700
     atom  20 type  1   force =     0.00000000    0.00000000    0.00000917
     atom  21 type  1   force =     0.00000000    0.00000000   -0.00008699
     atom  22 type  1   force =     0.00000000   -0.00000001    0.00026662
     atom  23 type  1   force =     0.00000000    0.00000001    0.00059280
     atom  24 type  1   force =     0.00000000    0.00000000   -0.00105593
     atom  25 type  1   force =     0.00000000    0.00000000    0.00615334
     atom  26 type  2   force =     0.00000000    0.00000000    0.01317569

as I said in the previous email, when SOC was not included the forces were
<1.0D-4Ry/au.

After many cycles it relaxes to structure B:


         1           Tl  tau(  1) = (   0.0000000  -0.0000002  -5.4750706  )
         2           Si  tau(  2) = (  -0.5000000  -0.2886754  -4.9286617  )
         3           Si  tau(  3) = (  -0.5000000  -0.2886751  -4.3089294  )
         4           Si  tau(  4) = (   0.0000000   0.0000001  -4.0900306  )
         5           Si  tau(  5) = (   0.0000000   0.0000005  -3.4646493  )
         6           Si  tau(  6) = (   0.5000000   0.2886757  -3.2486536  )
         7           Si  tau(  7) = (   0.5000000   0.2886753  -2.6244846  )
         8           Si  tau(  8) = (  -0.5000000  -0.2886750  -2.4089562  )
         9           Si  tau(  9) = (  -0.5000000  -0.2886748  -1.7850326  )
        10           Si  tau( 10) = (   0.0000000   0.0000002  -1.5698553  )
        11           Si  tau( 11) = (   0.0000000   0.0000013  -0.9460530  )
        12           Si  tau( 12) = (   0.5000000   0.2886761  -0.7311323  )
        13           Si  tau( 13) = (   0.5000000   0.2886753  -0.1074118  )
        14           Si  tau( 14) = (  -0.5000000  -0.2886753   0.1074118  )
        15           Si  tau( 15) = (  -0.5000000  -0.2886761   0.7311323  )
        16           Si  tau( 16) = (   0.0000000  -0.0000013   0.9460530  )
        17           Si  tau( 17) = (   0.0000000  -0.0000002   1.5698553  )
        18           Si  tau( 18) = (   0.5000000   0.2886748   1.7850326  )
        19           Si  tau( 19) = (   0.5000000   0.2886750   2.4089562  )
        20           Si  tau( 20) = (  -0.5000000  -0.2886753   2.6244846  )
        21           Si  tau( 21) = (  -0.5000000  -0.2886757   3.2486536  )
        22           Si  tau( 22) = (   0.0000000  -0.0000005   3.4646493  )
        23           Si  tau( 23) = (   0.0000000  -0.0000001   4.0900306  )
        24           Si  tau( 24) = (   0.5000000   0.2886751   4.3089294  )
        25           Si  tau( 25) = (   0.5000000   0.2886754   4.9286617  )
        26           Tl  tau( 26) = (   0.0000000   0.0000002   5.4750706  )




were the output says:


!    total energy              =    -207.08193686 Ry
     Harris-Foulkes estimate   =    -207.08193687 Ry
     estimated scf accuracy    <       0.00000002 Ry

    convergence has been achieved in  19 iterations

     Forces acting on atoms (Ry/au):

     atom   1 type  2   force =     0.00000000   -0.00000001   -0.00021452
     atom   2 type  1   force =     0.00000000    0.00000004   -0.00028392
     atom   3 type  1   force =     0.00000000    0.00000004   -0.00036455
     atom   4 type  1   force =     0.00000000   -0.00000001   -0.00029396
     atom   5 type  1   force =     0.00000000   -0.00000002   -0.00029563
     atom   6 type  1   force =     0.00000000   -0.00000008   -0.00028951
     atom   7 type  1   force =     0.00000000    0.00000003   -0.00018682
     atom   8 type  1   force =     0.00000000    0.00000006   -0.00026107
     atom   9 type  1   force =     0.00000000   -0.00000026   -0.00008411
     atom  10 type  1   force =     0.00000000    0.00000037   -0.00018718
     atom  11 type  1   force =     0.00000000   -0.00000073   -0.00001065
     atom  12 type  1   force =     0.00000000    0.00000047   -0.00011851
     atom  13 type  1   force =     0.00000000   -0.00000049    0.00004827
     atom  14 type  1   force =     0.00000000    0.00000049   -0.00004827
     atom  15 type  1   force =     0.00000000   -0.00000047    0.00011851
     atom  16 type  1   force =     0.00000000    0.00000073    0.00001065
     atom  17 type  1   force =     0.00000000   -0.00000037    0.00018718
     atom  18 type  1   force =     0.00000000    0.00000026    0.00008411
     atom  19 type  1   force =     0.00000000   -0.00000006    0.00026107
     atom  20 type  1   force =     0.00000000   -0.00000003    0.00018682
     atom  21 type  1   force =     0.00000000    0.00000008    0.00028951
     atom  22 type  1   force =     0.00000000    0.00000002    0.00029563
     atom  23 type  1   force =     0.00000000    0.00000001    0.00029396
     atom  24 type  1   force =     0.00000000   -0.00000004    0.00036455
     atom  25 type  1   force =     0.00000000   -0.00000004    0.00028392
     atom  26 type  2   force =     0.00000000    0.00000001    0.00021452


This is not forces <1.0D-4Ry/au, but its the most I could converge. The
energy is higher than in the first case. I do not know if it has something
to do with the problem, but the fully relativistic pseudopotentials were
checked in simpler systems giving good results. Thank you in advance

Julen
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