[Pw_forum] negative charge density!

[Eyvaz Isaev]

Hi, 

Did you try increase k-points instead of using only
Gamma-point? Besides, test also a little bit larger 
ecutrho, say 30Ry.

Bests,
Eyvaz.


--- Mousumi Upadhyay Kahaly <mousumi at jncasr.ac.in>
wrote:

> Hi all,
> 
>    This is a resubmission of my mail regarding
> charge density calculation.
> 
>
--------------------------------------------------------------------------
> 
> Dear all,
> 
>           I am trying to do charge analysis for
> Cd-di-acetate system. With
> the following files for pp.x and then chdens.x, as I
> am plotting
> the isosurfaces of charge densities with XCRYSDEN, I
> am getting
> some negative charge;
>        Minimum grid value= -0.498760, and maximum
> grid value= 1.09220.
> How come I get such negative values(mainly around
> the Cd atom, as found)
> which is not negligible? What is the meaning of this
> NEGATIVE charge
> density? Can anyone please tell me, what is the
> mistake that I have made &
> what should I do to get rid of this?
> 
>                                         Best
> regards,   Mousumi.
> 
> 1. Input file for SCF pw.x run:
>
=========================================================================
>   &CONTROL
>               calculation = 'scf' ,
>              restart_mode = 'from_scratch' ,
>                   tstress =.true.,
>                outdir =
> '/export/mousumi/PWSCF_2.0.1/Cd_2CH3COO/ELF/tmp//' ,
> pseudo_dir = '/export/mousumi/PWscf_GUI/pseudo/' ,
>                    prefix = 'Cd_di_acetate' ,
>  /
>  &SYSTEM
>                        ibrav = 8,
>                    celldm(1) = 50.000000,
>                    celldm(2) = 0.30,
>                    celldm(3) = 0.30,
>                          nat = 15,
>                         ntyp = 4,
>                      ecutwfc = 25.00000 ,
>                      ecutrho = 150.00000 ,
>                        nosym = .false. ,
>                         nbnd = 37,
>                  occupations = 'smearing' ,
>                      degauss = 0.003 ,
>                     smearing = 'methfessel-paxton' ,
>                        nspin = 1 ,
>                   lda_plus_u = .false. ,
>  /
>  &ELECTRONS
>                     conv_thr = 1.0d-12 ,
>                  mixing_beta = 0.3 ,
>  /
> ATOMIC_SPECIES
>     C    12.01000  C.pbe-van_bm.UPF
>     H     1.00000  H.pbe-van_bm.UPF
>     O    15.99990  O.pbe-van_bm.UPF
>    Cd    112.4000  Cd.pbe-van.UPF
> ATOMIC_POSITIONS  {angstrom}
> O       -2.181887203  -0.288129610  -0.491107761
> O       -1.981730329  -0.473233788   1.733566845
> C       -2.708815067  -0.432156029   0.673205720
> C       -4.208743648  -0.532432174   0.801074150
> H       -4.477821741  -1.131831132   1.680695448
> H       -4.617325903   0.482417907   0.942246198
> H       -4.646292897  -0.952999527  -0.113856718
> Cd      -0.137714936  -0.219807184   0.461048531
> C        2.434799121  -0.031519760   0.246012557
> O        1.729314564   1.038606335   0.354394821
> O        1.885568682  -1.194338232   0.239827517
> C        3.936349099   0.076394885   0.148653197
> H        4.228550980   1.056061785  -0.250634315
> H        4.360345258  -0.025882832   1.161749300
> H        4.338742013  -0.738423646  -0.467966988
> 
> K_POINTS {automatic}
>  1 1 1 0 0 0
>
==========================================================================
> 
> 2. After the pw.x run with above file, with files in
> "tmp" dir, file for pp.x
>
===========================================================================
>  &inputpp
>     prefix  = 'Cd_di_acetate'
>     outdir = 
> '/export/mousumi/PWSCF_2.0.1/Cd_2CH3COO/ELF/tmp//'
>     filplot = 'Cd_2CH3COO_chden'
>     plot_num = 0
>  /
>
==========================================================================
> 
> 3. Then, input file for chdens.x
>
==========================================================================
> &input
>     nfile = 1
>     filepp(1)='Cd_2CH3COO_chden'
>     iflag = 3
>     output_format = 5
> /
>
==========================================================================
> 
> 
> 
> 
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