[QE-developers] Fwd: [QE-users] dipole moment

[Paolo Giannozzi]

It seems to me that the printout is misleading: the first quantity should
be "polarization", not "dipole", and its units are not Debye

Paolo

---------- Forwarded message ---------
From: Ari P Seitsonen <Ari.P.Seitsonen at iki.fi>
Date: Mon, Nov 19, 2018 at 5:32 PM
Subject: Re: [QE-users] dipole moment
To: Quantum Espresso users Forum <users at lists.quantum-espresso.org>



Dear Sabike, [your affiliation please?]

   If I understand correctly your question, looking in the code in
'add_efield.f90':

...
      tot_dipole  = -el_dipole + ion_dipole
...

   IF ( iverbosity > 0 ) THEN
     WRITE( stdout, '(8X,"Elec. dipole ",1F15.4," Ry au, ", 1F15.4,"
Debye")' ) &
                                             el_dipole, (el_dipole*au_debye)
     WRITE( stdout, '(8X,"Ion. dipole  ",1F15.4," Ry au, ", 1F15.4,"
Debye")' ) &
                                           ion_dipole, (ion_dipole*au_debye)
   END IF

   WRITE( stdout, '(8X,"Dipole       ",1F15.4," Ry au, ", 1F15.4," Debye")'
) &
                   (tot_dipole* (omega/fpi)), ((tot_dipole*
(omega/fpi))*au_debye)

   WRITE( stdout, '(8x,"Dipole field ", 1F15.4," Ry au, ")') tot_dipole


Do those lines help? So something like
"Dipole = (-el_dipole + ion_dipole) * volume / (4 pi)". Was this what you
were looking for?

     Greetings from Lviv,

        apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
     Ecole Normale Supérieure (ENS), Département de Chimie, Paris
     Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935


On Sat, 17 Nov 2018, Sabike Ghasemi wrote:

> hi all,
> i am calculating dipole moment of water by pw.x.
> i do it correctly.but i don't understand "Elec. dipole" and " ion.
dipole" in out put and relation them wit
> dipole. can i help me ?
> input :
> &CONTROL
>     calculation  = "scf"
>     dipfield     = .TRUE.
>     disk_io      = "default"
>     iprint       = 1
>     max_seconds  =  8.64000e+04
>     nstep        = 100
>     outdir       = "./tmp1/"
>     prefix       = "H2Otest"
>     pseudo_dir   = "./"
>     restart_mode = "from_scratch"
>     tefield      = .TRUE.
>     title        = "H2Otest"
>     tprnfor      = .TRUE.
>     verbosity    = "high"
> /
>
> &SYSTEM
>     a           =  10
>     degauss     =  1.00000e-02
>     ecutrho     =  520
>     ecutwfc     = 130
>     ibrav       = 1
>     nat         = 3
>     ntyp        = 2
>     occupations = "smearing"
>     smearing    = "gaussian"
>   edir        = 1
>     emaxpos     =  0.9
>     eopreg      =  0.2
>  eamp        =  0.00000e+00
> input_dft = "PBE"
> vdw_corr = "Grimme-D2"
> /
>
> &ELECTRONS
>     conv_thr         =  1.00000e-06
>     electron_maxstep = 200
>     mixing_beta      =  7.00000e-01
>     startingpot      = "atomic"
>     startingwfc      = "atomic+random"
> /
>
> K_POINTS {automatic}
>  3  3  3  0 0 0
>
> ATOMIC_SPECIES
> O      15.99940  O.pbe-rrkjus.UPF
> H       1.00794  H.pbe-rrkjus.UPF
>
> ATOMIC_POSITIONS {angstrom}
> O       5   5   5
> H       5   4.209   5.563
> H       5   5.791   5.563
>
>
>
> output:
>
>
>      iteration #  6     ecut=   130.00 Ry     beta=0.70
>      Davidson diagonalization with overlap
>      c_bands:  1 eigenvalues not converged
>      ethr =  7.81E-08,  avg # of iterations =  6.6
>
>      negative rho (up, down):  0.438E-04 0.000E+00
>
>      Adding external electric field
>
>      Computed dipole along edir(3) :
>         Elec. dipole          0.0027 Ry au,           0.0068 Debye
>         Ion. dipole           0.0040 Ry au,         0.0101 Debye
>         Dipole                0.6902 Ry au,          1.7543 Debye
>         Dipole field          0.0013 Ry au
>
>         Potential amp.       -0.0389 Ry
>         Total length         15.1178 bohr
>
>
>      total cpu time spent up to now is      152.0 secs
>
>      End of self-consistent calculation
>
>
>
> best regards,
> sabike ghasemi
> phd student
>
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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