mirror of https://github.com/abinit/abinit.git
103 lines
4.6 KiB
Markdown
103 lines
4.6 KiB
Markdown
Information on the format 3 for pseudopotentials.
|
|
|
|
(Note: the implementation of format 3 was done by Fr. Detraux).
|
|
|
|
The format 3 for ABINIT pseudopotentials allows to use pseudopotentials
|
|
from the table I in the Phys. Rev. B 58, 3641 (1998) paper
|
|
by C. Hartwigsen, S. Goedecker and J. Hutter (HGH). This paper
|
|
presents LDA pseudopotentials for all elements from H to Rn. Some of them
|
|
are even presented twice, because of the possibility to include semi-core
|
|
states. Their accuracy has been demonstrated in the HGH paper, but note
|
|
that the energy cut-off needed to get this high accuracy might be
|
|
larger than the one usually needed for Troullier-Martins or other
|
|
pseudopotentials. So, convergence studies are very important !
|
|
|
|
A few lines must be added to the data mentioned in that table,
|
|
and are described in the present file. ABINITv1.5 is able to
|
|
read format 3 pseudopotential files, as well as later versions of ABINIT.
|
|
|
|
We will suppose that the user has the HGH table.
|
|
For the description that follows, we will focus on the Sn pseudopotential.
|
|
In the table (p. 3651), one finds:
|
|
|
|
Sn 4 0.605000 4.610912
|
|
0.663544 1.648791 -.141974 -.576546
|
|
0.745865 0.769355 -.445070
|
|
0.103931 0.005057
|
|
0.944459 0.225115
|
|
0.007066
|
|
|
|
These data must be put in the following format to be read by ABINIT
|
|
(this file is also found in the `~abinit/tests/Pspdir directory`,
|
|
with the name `50sn.psphgh`):
|
|
|
|
Hartwigsen-Goedecker-Hutter psp for Tin, from PRB58, 3641 (1998) paper
|
|
50 4 980509 zatom,zion,pspdat
|
|
3 1 2 0 2001 0 pspcod,pspxc,lmax,lloc,mmax,r2well
|
|
0.605000 4.610912 0 0 0 rloc, c1, c2, c3, c4
|
|
0.663544 1.648791 -.141974 -.576546 rs, h11s, h22s, h33s
|
|
0.745865 0.769355 -.445070 0 rp, h11p, h22p, h33p
|
|
0.103931 0.005057 0 k11p, k22p, k33p
|
|
0.944459 0.225115 0 0 rd, h11d, h23d, h33d
|
|
0.007066 0 0 k11d, k22d, k33d
|
|
|
|
|
|
First, the following three lines have been added at the beginning
|
|
of the data from the table:
|
|
|
|
Hartwigsen-Goedecker-Hutter psp for Tin, from PRB58, 3641 (1998) paper
|
|
50 4 980509 zatom,zion,pspdat
|
|
3 1 2 0 2001 0 pspcod,pspxc,lmax,lloc,mmax,r2well
|
|
|
|
Similar lines must be added to the data for other elements, in order
|
|
to make them readable by ABINIT.
|
|
|
|
Line 1 is simply a header, that might include any information, and that will
|
|
be printed without modification in the output of ABINIT.
|
|
|
|
Line 2 describes:
|
|
|
|
- the atomic number (zatom);
|
|
- the ionic charge (zion, number of valence electrons);
|
|
- the date of pseudopotential generation.
|
|
|
|
The two first information are crucial, the third one is not
|
|
really important. The atomic number is 1 for Hydrogen, 8 for Oxygen, and so on.
|
|
The ionic charge should be the same number as the second number mentioned
|
|
in the data table (described as 'Zion' in section VI of the paper)
|
|
|
|
Line 3 describes:
|
|
|
|
- the format of the pseudopotential (pspcod ; must be 3 for this format);
|
|
- the XC functional used to generate the pseudopotential (pspxc; here, must be 1)
|
|
- the maximal angular momentum of the wavefunctions described
|
|
in the pseudopotential file
|
|
(lmax=0 if purely local pseudopotential: H, He, Li^sc, Be^sc ;
|
|
lmax=1 for s and p projectors : Li, B ... Ar, K^sc, Au ;
|
|
lmax=2 for s, p and d projectors : K, Ca, ... Cs, Ba, Hf^sc ... Pt^sc,
|
|
Au^sc ... Rn ;
|
|
lmax=3 for s, p, d and f projectors : Cs^sc, Ba^sc, La^sc ... Lu^sc )
|
|
- lloc has no meaning, and is set to 0
|
|
- mmax has no meaning, and is set to 2001
|
|
- the last number can be set to 0 .
|
|
|
|
The lines that follow these three lines
|
|
are generated from the data in the table, though the name of the
|
|
element and Zion are not reproduced. Note also that
|
|
each line has to be completed with zeroes, to give the format presented
|
|
at the beginning of the section VI of the HGH paper :
|
|
five columns for the first of these lines,
|
|
then 4 columns for each projector, and 3 columns for the spin-orbit splitting.
|
|
For readability, the meaning of each number has also been added
|
|
in our example pseudopotential file
|
|
(for example, 'rloc, c1, c2, c3, c4' ) but these are NOT read by ABINIT.
|
|
Thus, unlike the zeroes, it is not important to add them to the
|
|
data from the table.
|
|
|
|
Inside ABINIT, the pseudopotential with format 1 will be treated by
|
|
the routine psp2in.f, that calls psp2lo.f (local part) and
|
|
psp2nl.f (non-local part).
|
|
|
|
As a matter of numerical accuracy, note that the integral
|
|
of (V(r)+Zion/r) r^2 in psp2lo.f is performed analytically without cut-off.
|