[Pw_forum] E-field: please any response!

[Giuseppe Mattioli]

Dear Jaret
Sometimes it happens that we simply do not have any useful answer...  
You are mixing an impressive amount of "non standard" DFT features  
like electric field, full DFT+U method, in a junction between strongly  
correlated, open-shell systems. If something goes wrong it is *very  
difficult* to say what! So try first "brute force":

     mixing_beta=0.02,
     electron_maxstep=1000

If you still do not reach convergence, then start simplifying your  
system toward plain DFT. I do not know why you are using the sawtooth  
potential, but you could also flick through the documentation of all  
the assume_isolated='esm' cases. One of them might be useful to you,  
and the calculation are quite stable, at least in my experience.
HTH
Giuseppe

Quoting Jaret Qi <jaretqi at yahoo.com>:

> Hello QE users,I am trying to apply saw-like electric field on a  
> structure (input is given below), but it reached 500 step without  
> converging, I do not know if something wrong with the input file,  
> please take a look on the input:  
> ---------------------------------------------------------------------part of  
> the output:     total energy              =   -3007.64456350 Ry
>      Harris-Foulkes estimate   =   -3007.64456538 Ry
>      estimated scf accuracy    <       0.00002171 Ry
>
>      total magnetization       =     0.39 Bohr mag/cell
>      absolute magnetization    =     3.46 Bohr mag/cell
>
>      End of self-consistent calculation
>
>      convergence NOT achieved after 500 iterations: stopping
> ---------------------------------------------------------------------
> Input: &control
>     calculation  = 'relax'
>     restart_mode = 'from_scratch'
>     pseudo_dir   = './'
>     outdir       = './'
>     nstep = 100 ,
>     tefield = .true.
>     dipfield = .true.
>  /
>  &system
>     ibrav=0
>     celldm(1)=7.540006694
>     nat=40
>     ntyp=7
>     ecutwfc = 30 ,
>     ecutrho=300
>     occupations='smearing'
>     degauss=0.02
>     nspin=2
>     starting_magnetization(2) = 1 
>     lda_plus_u = .true.
>     Hubbard_U(2)= 2
>     Hubbard_J0(2)=0.7
>     edir = 3
>     eamp = 0.00
>     emaxpos = 0.7
>     eopreg = 0.1
>  /
>  &electrons
>     mixing_beta=0.3,
>     electron_maxstep=500
> /
> &IONS
> /
>
> ATOMIC_SPECIES
> -------------------------------
> ATOMIC_POSITIONS (alat)
> La       0.001181668   0.001181668   6.050060401
> Mn       0.469738707   0.469738707   6.565742621
> O        0.469473688   0.469473688   6.085964317
> O        0.468843692   0.000348383   6.538606525
> O        0.000348383   0.468843692   6.538606525
> Sr       0.001039864   0.001039864   7.064792061
> Mn       0.469676094   0.469676094   7.557901982
> O        0.469624727   0.469624727   7.056571078
> O        0.468925802   0.000293611   7.575881614
> O        0.000293611   0.468925802   7.575881614
> La       0.000993325   0.000993325   8.089910079
> Mn       0.469504247   0.469504247   8.593701257
> O        0.469318550   0.469318550   8.039436909
> O        0.469234084   0.000344639   8.527412698
> O        0.000344639   0.469234084   8.527412698
> Pb      -0.014392827  -0.014392827   0.254329743    1   1   0
> Ti       0.449335594   0.449335594   0.744524878    1   1   0
> O        0.445630194   0.445630194   0.292667664    1   1   0
> O        0.446866894  -0.020789811   0.782939868    1   1   0
> O       -0.020789811   0.446866894   0.782939868    1   1   0
> Pb      -0.016727738  -0.016727738   1.262175978
> Ti       0.450604754   0.450604754   1.820354388
> O        0.447848259   0.447848259   1.358571068
> O        0.447194479  -0.020103191   1.926302938
> O       -0.020103191   0.447194479   1.926302938
> Pb      -0.006882381  -0.006882381   2.371864847
> O        0.446926722   0.446926722   2.551971810
> O        0.468151164  -0.002813857   3.241466866
> O       -0.002813857   0.468151164   3.241466866
> Pb      -0.004895228  -0.004895228   3.694395477
> Ti       0.469851616   0.469851616   4.313940138
> O        0.470070311   0.470070311   3.861981065
> O        0.469479771   0.000630908   4.426237872
> O        0.000630908   0.469479771   4.426237872
> Pb       0.002684401   0.002684401   4.871067455
> Ti       0.470100084   0.470100084   5.489734431
> O        0.469191796   0.469191796   5.033815628
> O        0.469294913   0.000554244   5.600299218
> O        0.000554244   0.469294913   5.600299218
> Zr       0.464031631   0.464031631   3.060505444
> K_POINTS {automatic}
>   6 6 1 0 0 0
>
> CELL_PARAMETERS alat
>    0.937980317  -0.000009219   -0.000131497
>   -0.000009219   0.937980317   -0.000131497
>   -0.001221078  -0.001221078   15.641997242
>
>
> --------------------------thank youJaret, QiASU


-- 
********************************************************
- Article premier - Les hommes naissent et demeurent
libres et égaux en droits. Les distinctions sociales
ne peuvent être fondées que sur l'utilité commune
- Article 2 - Le but de toute association politique
est la conservation des droits naturels et
imprescriptibles de l'homme. Ces droits sont la liberté,
la propriété, la sûreté et la résistance à l'oppression.
********************************************************

    Giuseppe Mattioli
    CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
    v. Salaria Km 29,300 - C.P. 10
    I 00015 - Monterotondo Stazione (RM)
    Tel + 39 06 90672836 - Fax +39 06 90672316
    E-mail: <giuseppe.mattioli at ism.cnr.it>
    http://www.ism.cnr.it/en/staff/giuseppe-mattioli/
    ResearcherID: F-6308-2012