[QE-users] Ionic + hartree potential

[Offermans Willem]

Dear Quantum Espresso friends,

I have relaxed a Pt(111) surface with 5 metal layers and S_2 symmetry :)

To validate the calculations, I like to plot the x,y-averaged electrostatic potential
along the z-coordinate of the unit cell.

I have used pp.x and the following input file (pt.ppi) to obtain the values for the electrostatic 
potential on a grid. Please correct me if I’m wrong, but I thought it was the FFT grid.

pt.ppi:
<snip>
$inputPP
   outdir='.'
   plot_num=11
   filplot = 'Pt111_5M3V2x2.estatic.pot'
/
</snip>

As expected `pp.x < pt.ppi` yielded Pt111_5M3V2x2.estatic.pot.

I then used average.x and the following input file (pt.avi) to obtain the x,y-averaged values
for the electrostatic potential along the z-coordinate of the unit cell. 

pt.avi
<snip>
1
Pt111_5M3V2x2.estatic.pot
1.0
1440
3
3.835000000
</snip>

`average.x < pt.avi` yielded a avg.dat file.

I then plotted the the first and second column of avg.dat file with gnuplot. The plot is attached to this e-mail.

According to https://www.quantum-espresso.org/Doc/INPUT_PP.html#idm24: <https://www.quantum-espresso.org/Doc/INPUT_PP.html#idm24:> "

All potentials have the dimension of an energy (e*V, not V).”

So, the graph shows that the electrostatic potential varies between ca. -0.4 eV and ca. 1 eV.
So the vacuum electrostatic potential is about 1 eV.

According to the pw.x calculation, the Fermi energy is 8.2481 eV

This is not consistent to my idea. I would have expected a Fermi energy smaller than 1 eV, or a
vacuum electrostatic potential > 8.2481 eV.

What am I doing wrong? Did I plot the electrostatic potential?






Met vriendelijke groeten,
Mit freundlichen Grüßen,
With kind regards,


Willem Offermans
Researcher Electrocatalysis SCT
VITO NV | Boeretang 200 | 2400 Mol
Phone:+32(0)14335263 Mobile:+32(0)492182073 

Willem.Offermans at Vito.be

 

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