[Pw_forum] Relaxation with Spin-Orbit Coupling

Dal Corso Andrea dalcorso at sissa.it
Tue Jul 13 12:23:15 CEST 2010


Difficult to say. Are you sure about the Tl PP. A ghost in particular
could cause the effects that you report. 

Andrea  


On Tue, 2010-07-13 at 11:59 +0200, Julen Ibanez Azpiroz wrote:
> 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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-- 
Andrea Dal Corso                    Tel. 0039-040-3787428
SISSA, Via Beirut 2/4               Fax. 0039-040-3787528
34151 Trieste (Italy)               e-mail: dalcorso at sissa.it




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