How to generate a
pseudopotential
Objectives
Generate a norm-conserving pseudopotential using ATOM
Description of the input file of the ATOM code for a
pseudopotential generation
A title for the job
N 1s2
pg  Pseudopotential generation
core
Chemical
symbol of the
atom
Principal
quantum
number
Angular
quantum
number
Cutoff radii for the
Occupation
different shells
(in bohrs)
(spin up)
(spin down)
2s2 2p3 3d0 4f0
valence
Number of core
and valence
orbitals
Exchange-and correlation functional
ca  Ceperley-Alder (LDA)
wi  Wigner (LDA)
hl  Hedin-Lundqvist (LDA)
bh  von-Barth-Hedin (LDA)
gl  Gunnarson-Lundqvist (LDA)
pb  Perdew-Burke-Ernzerhof, PBE (GGA)
rv  revPBE (GGA)
rp  RPBE, Hammer, Hansen, Norvskov (GGA)
ps  PBEsol (GGA)
wc  Wu-Cohen (GGA)
+s if spin (no relativistic)
+r if relativistic
bl  BLYP Becke-Lee-Yang-Parr (GGA)
am AM05 by Armiento and Mattson (GGA)
vw  van der Waals functional
How to run a pseudopotential generation with ATOM
Run the script
The pseudopotentials
will be on the same
parent directory:
.vps (unformatted)
.psf (formatted)
.xml (in XML format)
Different output files in a
new directory (same
name as the input file
without the .inp
extension)
An explanation of the different files can be
found in the ATOM User’s Guide (page 6)
Plotting the all electron and pseudo charge densities
$ gnuplot –persist charge.gplot
(To generate a figure on the screen using gnuplot)
$ gnuplot charge.gps
(To generate a postscript file with the figure)
The core and the charge densities are angularly integrated (multiplied by
)
Charge densities (electrons/bohr)
The PS and AE valence
charge densities are
equal beyond the cutoff
radii
Small peak in the AE
valence charge density
due to orthogonality with
AE core
r (bohr)
Plotting the all pseudopotenial information
$ gnuplot –persist pseudo.gplot
(To generate a figure on the screen using gnuplot)
$ gnuplot pseudo.gps
(To generate a postscript file with the figure)
AE and PS
wavefunctions
Real space
pseudopotential
AE and PS
logarithmic
derivatives
Fourier transformed
pseudopotential
The more Fourier
components, the
harder the
pseudopotential
A figure like this for each angular momentum shell in the valence
Plotting the real-space pseudopotentials
(To generate a figure on the screen using gnuplot)
$ gnuplot pots.gps
(To generate a postscript file with the figure)
Pseudopotential (Ry)
$ gnuplot –persist pots.gplot
Beyond the largest cutoff
radius, the pseudopotential
tends to
r (bohr)
Plotting the unscreened and screened pseudopoten
(To generate a figure on the screen using gnuplot)
$ gnuplot scrpots.gps
(To generate a postscript file with the figure)
Pseudopotential (Ry)
$ gnuplot –persist scrpots.gplot
r (bohr)
Exploring the output file
$ vi OUT
Comparing AE and PS eigenvalues
$ grep ‘&v’ OUT
Eigenvalues (in Ry)
The AE and PS eigenvalues are not exactly identical because the
pseudopotentials are changed slightly to make them approach their limit tails
faster
If the cutoff radii are negative
0,6
In the OUT file,
these radii are written in
radial part of the 4s orbital
position of the last peak: 2.943 Bohr
0,4
0,2
0,0
position of the last node: 1.252 Bohr
-0,2
0,0
10,0
5,0
15,0
distance to nuclei (Bohr)
20,0