How to calculate the charge density of Silicon

We need 4 files

algerien1970@linux-wipm:~/abinitio/QE-tutorials/Si_rho> ls
Si.pbe-rrkj.UPF  Si.pp2.in  Si.pp3.in Si.scf.in  Si.scf.out

 

Si.scf.in

&CONTROL
 calculation='scf',
 restart_mode='from_scratch',
 prefix='si',
 pseudo_dir='./',
 outdir='./OUT_RHO/',
/
&SYSTEM
 ibrav=2,
 celldm(1)=10.2625,
 nat=2,
 ntyp=1,
 ecutwfc=60.0,
 ecutrho=720.0,
/
&ELECTRONS
 mixing_beta=0.7,
 conv_thr=1d-8,
/
ATOMIC_SPECIES
 Si 28.0855 Si.pbe-rrkj.UPF
ATOMIC_POSITIONS (alat)
Si  0.00  0.00  0.00
Si  0.25  0.25  0.25
K_POINTS automatic
4 4 4 1 1 1

Si.pp2.in   for 2D representation

&INPUTPP
 outdir='./OUT_RHO/',
 prefix='si',
 plot_num=0,
/
&plot
  iflag=2
 output_format=2
 x0(1)=0.0, x0(2)=0.0, x0(3)=0.0
 e1(1)=1.0, e1(2)=1.0, e1(3)=0.0
 e2(1)=0.0, e2(2)=0.0, e2(3)=1.0
 fileout=si-rho2D.pl,
 nx=40, ny=30,
/

Si.pp3.in     for 3D representation

&INPUTPP
 outdir='./OUT_RHO/',
 prefix='si',
 plot_num=0,
/
&PLOT
 iflag=3,
 output_format=6,
 fileout='si_rho.cube',
 nx=64,ny=64,nz=64,
/

 Si.pbe-rrkjus.UPF

You can download the file using the following command

$ wget https://www.quantum-espresso.org/upf_files/Si.pbe-rrkj.UPF --no-check-certificate

 

1. SCF calculation

algerien1970@linux-wipm:~/abinitio/QE-tutorials/Si_rho> pw.x < Si.scf.in |tee Si.scf.out

 

!    total energy              =     -15.74123364 Ry
     estimated scf accuracy    <          4.8E-10 Ry

     The total energy is the sum of the following terms:
     one-electron contribution =       4.77320847 Ry
     hartree contribution      =       1.09504988 Ry
     xc contribution           =      -4.81265521 Ry
     ewald contribution        =     -16.79683678 Ry

     convergence has been achieved in   7 iterations

     Writing output data file ./OUT_RHO/si.save/

2. Charge density calculation and plotting

 For 2D representation

algerien1970@linux-wipm:~/abinitio/QE-tutorials/Si_rho> pp.x < Si.pp2.in |tee Si.pp2.out

algerien1970@linux-wipm:~/abinitio/QE-tutorials/Si_rho> plotrho.x 
     Input file > si_rho2D.pl
si_rho2D.pl: file not found
     Input file > si-rho2D.pl
r0   :   0.0000  0.0000  0.0000
tau1 :   1.0000  1.0000  0.0000
tau2 :   0.0000  0.0000  1.0000
read   2 atomic positions
output file > si_rho2D.ps
Read  40 * 30  grid
Logarithmic scale (y/n)? > n
Bounds:     0.003274    0.086600
min, max, # of levels > 0.0 0.07 6

Reference: http://www.fisica.uniud.it/~giannozz/Didattica/MetNum/LectureNotes/metnum-ex4.pdf

https://studylib.net/doc/18426955/hands-on-tutorial-on-the-quantum 

 For 3D representation

algerien1970@linux-wipm:~/abinitio/QE-tutorials/Si_rho> pp.x < Si.pp3.in |tee Si.pp3.out

We will get the file si_rho.cube to be plooted by VESTA tool

Reference: https://www.youtube.com/watch?v=dkg60f1gEp8 

                   https://drive.google.com/file/d/1JLoA1odqq2dSZ5kaGZs8o3QeNM14gFkE/view

Input data: https://drive.google.com/file/d/1Xdo_3uFXyY1uZCsLWFvRCYU8vqeljKtH/view