[Pw_forum] problem getting electronuc dipole moment

[Axel Kohlmeyer]

On Fri, 22 Jul 2005, Mousumi Upadhyay Kahaly wrote:

MK> Dear All,
MK> 
MK>           I am trying to compute electronic and ionic dipole moments of an
MK> isolated H2 molecule in a big box. For this, after relaxation, I
MK> am running one scf step followed by a pp.x run and then chdens.x
MK> run(with the option idpol = 1).

MK> 
MK>           The problem is that, irrespective of the positions of the H2
MK> molecule in the big box, always it comes that charge density
MK> inside the Wigner-Seitz cell = 0.00000000 & hence, electronic
MK> dipole moment is sero. Have I done something wrong may be, while

i may be missing something here, but the h2 molecule has 
no dipole moment (unless you polarize it).

axel.

MK> setting up the input files??? Because this is the case for any
MK> molecule in any position within a box of any size. Can anyone
MK> please help me to get rid of this problem?
MK> 
MK>           All the inputs files i am using(one case: when the molecule
MK> centre is in the centre of the box) are written below.
MK> 
MK>                                             Best regards,  mousumi.
MK> ==========================================================================
MK> 1. Input file for scf run: pw.x input file
MK> 
MK>  &CONTROL
MK>               calculation = 'scf' ,
MK>                    tstress=.true.,
MK>              restart_mode = 'from_scratch' ,
MK>        outdir =
MK> '/export/mousumi/PWSCF_2.0.1/H2/PostProcess/dipole_mom/tmp2//' ,
MK>                   pseudo_dir = '/export/mousumi/PWscf_GUI/pseudo/' ,
MK>                       prefix = 'H2' ,
MK>  /
MK>  &SYSTEM
MK>                        ibrav = 1,
MK>                    celldm(1) = 30.00000,
MK>                          nat = 2,
MK>                         ntyp = 1,
MK>                      ecutwfc = 30.00000  ,
MK>                      ecutrho = 180.00000 ,
MK>                        nosym = .false. ,
MK>                         nbnd = 5,
MK>                        nspin = 1 ,
MK>                   lda_plus_u = .false. ,
MK>  /
MK>  &ELECTRONS
MK>                     conv_thr = 1.0d-8 ,
MK>     /
MK>  &IONS
MK>                      upscale = 10.0 ,
MK>  /
MK> ATOMIC_SPECIES
MK>     H    1.00000  H.pbe-van_bm.UPF
MK> ATOMIC_POSITIONS {angstrom}
MK> H        7.70055287150   7.70055287150   7.70055287150
MK> H        8.15472682850   8.15472682850   8.15472682850
MK> K_POINTS {automatic}
MK> 1  1  1  0  0  0
MK>               mixing_beta = 0.6 ,
MK> 
MK> =====================================================================
MK> 2. With the files created in temp2/ directory from the above run,
MK>                         input file for pp.x
MK>  &inputpp
MK>     prefix  = 'H2'
MK>     outdir =
MK> '/export/mousumi/PWSCF_2.0.1/H2/PostProcess/dipole_mom/tmp2//'
MK>     filplot = 'H2_chdens2'
MK>     plot_num = 0
MK>  /
MK> 
MK> =======================================================================
MK> 3. With the 'H2_chdens2' file created in the above run, file for
MK>                                  running chdens.x
MK> &input
MK>     nfile = 1
MK>     filepp(1)='H2_chdens2'
MK>     iflag = 3
MK>     plot_out = 1
MK>     idpol = 1
MK>     output_format = 5
MK> /
MK> 
MK> =========================================================================
MK> 
MK> 
MK> _______________________________________________
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MK> Pw_forum at pwscf.org
MK> http://www.democritos.it/mailman/listinfo/pw_forum
MK> 
MK> 

-- 

=======================================================================
Dr. Axel Kohlmeyer   e-mail: axel.kohlmeyer at theochem.ruhr-uni-bochum.de
Lehrstuhl fuer Theoretische Chemie          Phone: ++49 (0)234/32-26673
Ruhr-Universitaet Bochum - NC 03/53         Fax:   ++49 (0)234/32-14045
D-44780 Bochum  http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/
=======================================================================
If you make something idiot-proof, the universe creates a better idiot.