[Pw_forum] problem getting electronuc dipole moment

[Andrea Dal Corso]

On Fri, 2005-07-22 at 00:18 +0530, Mousumi Upadhyay Kahaly wrote:
> Dear All,
> 
>           I am trying to compute electronic and ionic dipole moments of an
> isolated H2 molecule in a big box. For this, after relaxation, I
> am running one scf step followed by a pp.x run and then chdens.x
> run(with the option idpol = 1).
> 
>           The problem is that, irrespective of the positions of the H2
> molecule in the big box, always it comes that charge density
> inside the Wigner-Seitz cell = 0.00000000 & hence, electronic
> dipole moment is sero. Have I done something wrong may be, while
> setting up the input files??? Because this is the case for any
> molecule in any position within a box of any size. Can anyone
> please help me to get rid of this problem?
> 
>           All the inputs files i am using(one case: when the molecule
> centre is in the centre of the box) are written below.
> 
>                                             Best regards,  mousumi.
> ==========================================================================
> 1. Input file for scf run: pw.x input file
> 
>  &CONTROL
>               calculation = 'scf' ,
>                    tstress=.true.,
>              restart_mode = 'from_scratch' ,
>        outdir =
> '/export/mousumi/PWSCF_2.0.1/H2/PostProcess/dipole_mom/tmp2//' ,
>                   pseudo_dir = '/export/mousumi/PWscf_GUI/pseudo/' ,
>                       prefix = 'H2' ,
>  /
>  &SYSTEM
>                        ibrav = 1,
>                    celldm(1) = 30.00000,
>                          nat = 2,
>                         ntyp = 1,
>                      ecutwfc = 30.00000  ,
>                      ecutrho = 180.00000 ,
>                        nosym = .false. ,
>                         nbnd = 5,
>                        nspin = 1 ,
>                   lda_plus_u = .false. ,
>  /
>  &ELECTRONS
>                     conv_thr = 1.0d-8 ,
>     /
>  &IONS
>                      upscale = 10.0 ,
>  /
> ATOMIC_SPECIES
>     H    1.00000  H.pbe-van_bm.UPF
> ATOMIC_POSITIONS {angstrom}
> H        7.70055287150   7.70055287150   7.70055287150
> H        8.15472682850   8.15472682850   8.15472682850
> K_POINTS {automatic}
> 1  1  1  0  0  0
>               mixing_beta = 0.6 ,
> 
> =====================================================================
> 2. With the files created in temp2/ directory from the above run,
>                         input file for pp.x
>  &inputpp
>     prefix  = 'H2'
>     outdir =
> '/export/mousumi/PWSCF_2.0.1/H2/PostProcess/dipole_mom/tmp2//'
>     filplot = 'H2_chdens2'
>     plot_num = 0
>  /
> 
> =======================================================================
> 3. With the 'H2_chdens2' file created in the above run, file for
>                                  running chdens.x
> &input
>     nfile = 1
>     filepp(1)='H2_chdens2'
>     iflag = 3
>     plot_out = 1
>     idpol = 1
>     output_format = 5
> /
> 


The dipole moment is not calculated with all values of output_format. 
A warning message appears in the output if the dipole is not calculated.


Best Regards,

Andrea 


> =========================================================================
> 
> 
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
-- 
Andrea Dal Corso                    Tel. 0039-040-3787428
SISSA, Via Beirut 2/4               Fax. 0039-040-3787528
34014 Trieste (Italy)               e-mail: dalcorso at sissa.it