[QE-users] Calculating the total (valence + core) charge

[Jan Oliver Oelerich]

Hi QE users,

I need the total charge density (including core electrons) and 
calculated it using pp.x's `plot_num=21` method after a converged SCF 
calculation. (See below for the pw.x and pp.x input files).

Summing up the values of the `density.cube` file and multiplying the 
result with the volume element (dV=V/(96*96*180), V in bohr^3) gets me 
nothing even close to the expected value of 76 electrons. (I get 2.7..)

What am I missing here? Are my grids too small or is it something about 
the units that I got wrong?

Thanks and cheers,
Jan Oliver Oelerich

-------pw.x----------
&CONTROL
     calculation = 'scf',
     prefix     = 'GaN',
     pseudo_dir = '/opt/QEPseudos/pslibrary.1.0.0/pbe/PSEUDOPOTENTIALS',
     outdir     = './out',
     wf_collect = .TRUE.,
/
&SYSTEM
     ecutwfc          = 30.0
     ntyp             = 2
     nat              = 4
     ibrav            = 0
     nr1              = 96
     nr2              = 96
     nr3              = 180
/
&ELECTRONS
/

ATOMIC_SPECIES
Ga 69.723   Ga.pbe-dn-kjpaw_psl.1.0.0.UPF
N  14.007   N.pbe-n-kjpaw_psl.1.0.0.UPF

K_POINTS automatic
6 6 4  0 0 0

CELL_PARAMETERS angstrom
3.18600000000000 0.00000000000000 0.00000000000000
-1.59300000000000 2.75915693645722 0.00000000000000
0.00000000000000 0.00000000000000 5.18600000000000

ATOMIC_POSITIONS angstrom
Ga 0.0000000000 0.0000000000 0.0000000000
N 0.0000000000 1.8394379576 0.6440642113
Ga 0.0000000000 1.8394379576 2.5930000000
N 0.0000000000 0.0000000000 3.2370642113


-------pp.x------------
&inputpp
     prefix  = 'GaN'
     outdir = './out'
     filplot = 'electron_density.dat'
     plot_num = 21
/
&plot
     nfile = 1
     filepp(1) = 'electron_density.dat'
     weight(1) = 1.0
     iflag = 3
     output_format = 6
     fileout = 'density.cube'
/


-- 
Dr. Jan Oliver Oelerich
Philipps-Universität Marburg

Faculty of Physics and Material Sciences Center
Addr.: Room 02D35, Hans-Meerwein-Straße 6, 35032 Marburg, Germany
Phone: +49 6421 2822260

Semiconductor Theory, Department of Physics
Addr.: Room 01001, Mainzer Gasse 33, 35032 Marburg, Germany
Phone: +49 6421 2824335

Mail : jan.oliver.oelerich at physik.uni-marburg.de
Web  : http://academics.oelerich.org