[QE-users] possible little bug in post-processing + electric field ?

Giovanni Cantele giovanni.cantele at spin.cnr.it
Wed Apr 18 12:47:41 CEST 2018

Dear all,

I’m using pp.x, 6.2 version, and trying to plot the sawtooth electric field potential (if present) (plotnum=12), in the presence of
dipole correction. However, after successfully accomplishing the pw.x run, I find that that the sawtooth potential saved by pp.x is
everywhere zero and the following message appears in the output of pp.x:
     Message from routine punch_plot:
     e_field is not calculated

However, if using 5.4.0 with the SAME input files, the output of pp.x says, for example (in a sample run)
     Calling punch_plot, plot_num =  12

     Adding external electric field

     Computed dipole along edir(3) : 
        Dipole               -0.0216 Ry au,         -0.0550 Debye
        Dipole field         -0.0000 Ry au

        Potential amp.        0.0014 Ry
        Total length         17.9524 bohr

I realise that since 5.4.0 the format of some (or maybe all) files within outdir has changed, because for example
in 5.4.0 I find data-file.xml that contains a line such as
 <HAS_ELECTRIC_FIELD type="logical" size="1">
that is present NOWHERE in the filed saved by pw.x 6.2. On the other hand, other fields of xml files, such as field_direction
or maximum_position are present in the outputs of both 6.2 and 5.4.0 even though with slightly different formats.

Just to let someone try if I’m incorrectly using pp.x or if a possible bug has been introduced from 5.4.0 to 6.2, this is a sample, quick
run that reproduces the error:

================ prova.scf.in
    calculation  = 'scf'
    title        = 'prova'
    restart_mode = 'from_scratch'
    outdir       = './tmp/'
    prefix       = 'prova'
    pseudo_dir   = './'
    tefield      = .true.
    dipfield     = .true.
    ibrav        = 1
    a            = 10.0
    nat          = 1
    ntyp         = 1
    ecutwfc      = 20
    occupations  = 'smearing'
    smearing     = 'mv' 
    degauss      = 0.015
    edir         = 3
    eamp         = 0.0
    emaxpos      = 0.638889
    eopreg       = 0.05
         O    15.9994  	  O.pbe-n-kjpaw_psl.1.0.0.UPF
O     0.0   0.0   0.0
K_POINTS { gamma }

================ prova.pp.in
    prefix        = 'prova'
    outdir        = './tmp/'
    filplot       = 'prova.pp'
    plot_num      = 12

Could you please give me an advice on whether I’m using in the wrong way pp.x or there is an issue in
6.2 versus 5.4.0? If the latter applies, is the problem only related to pp.x or it affects also the results of
scf/relax runs?

Thanks in advance,



Giovanni Cantele, PhD
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: giovanni.cantele at spin.cnr.it
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: http://people.fisica.unina.it/~cantele

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