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--- developers:pseudos:psp1_format [2015/02/25 13:24] – created Matteo Giantomassi
+++ developers:pseudos:psp1_format [2020/08/10 18:06] (current) – Xavier Gonze
@@ Line 1: / Line 1: @@
+==== Information on the format 1 for pseudopotentials. ====
+The format 1 for ABINIT pseudopotentials allows to use pseudopotentials
+from the set of LDA pseudotentials for the whole periodic table,
+build by DC Allan and A.Khein. They have been generated according to the Troullier-Martins technique.
+See ~abinit/doc/users/bibliography.html for the corresponding references.
+The pspcod=1 psp files are formatted data files
+which give potentials and projector functions on a real space radial grid.
+Firstly, the radial grid runs from index 0 to 2000 (2001 points),
+with grid points given by the following equation (given as fortran):
+      nmax=2000
+      do j=0,nmax
+        x=dble(j)/dble(nmax)
+        r(j)=100.d0*(x+.01d0)**5-1.d-8
+      end do
+The psp file consists of a number of header lines followed by the
+data on the radial grid.
+The header section is as follows:
+     title  (single 80 character line)
+     zatom, zion, pspdat
+     pspcod, pspxc, lmax, lloc, mmax, r2well
+     ...then, for l=0 to lmax, the following 2 lines:
+      l,e99.0,e99.9,nproj,rcpsp
+      rms,ekb1,ekb2,epsatm
+     ...finally one more line:
+      rchrg,fchrg,qchrg
+The data may be located anywhere on the line as long as it is provided
+in the order indicated (it is read with free format).
+In the case of Si with lmax=2, the header may look like the following 10 lines:
+  Si  Fri Oct 08 11:18:59 1993
+.00000   4.00000    930920                zatom, zion, pspdat
+    1    2    2      2001    .00050      pspcod,pspxc,lmax,lloc,mmax,r2well
+  19.464  25.000    2   1.8971118        l,e99.0,e99.9,nproj,rcpsp
+    .00112760   6.1457108933   4.4765165955  29.74712295   rms,ekb1,ekb2,epsatm
+  21.459  28.812    2   1.8971118        l,e99.0,e99.9,nproj,rcpsp
+    .00119946   3.2090654032   2.0935248528  19.11150542   rms,ekb1,ekb2,epsatm
+   8.223  21.459    0   1.8971118        l,e99.0,e99.9,nproj,rcpsp
+    .00098688    .0000000000    .0000000000  -3.97301006   rms,ekb1,ekb2,epsatm
+.70000000000000     .22513330685109     .96523597101781   rchrg,fchrg,qchrg
+     zatom is the atomic number of the atom (14 for Si)
+     zion is the number of valence electrons (4 for Si)
+     pspdat is a code revision date (930920 for this case)
+     pspcod is another index describing the code (1 for this case)
+     pspxc is an index showing the choice of exchange-correlation (1)
+     lmax is the highest angular momentum for which a pseudopotential
+      is defined, which is also used for the local potential (2)
+     lloc is the angular momentum used for the local potential (2)
+     mmax is the number of grid points (2001)
+     r2well is the prefactor of a harmonic well sometimes used to bind
+      electrons which would otherwise be unbound in lda (.00050)
+     l is the angular momentum (0, 1, or 2 for Si for this case)
+     e99.0 is the planewave cutoff needed to converge to within 99.0% of the
+      kinetic energy of the atom (various numbers for various l)
+     e99.9 is the planewave cutoff needed to converge to within 99.9% of the
+      kinetic energy of the atom (various numbers for various l)
+     nproj is the number of projection functions used for each l (2)
+     rcpsp is the pseudopotential core radius
+     rms is a measure of pseudopotential quality reflecting the value of the
+      penalty function in designing the potential
+     ekb1, ekb2 are the Kleinman-Bylander energies for each projection
+      function for each l
+     epsatm is the integral Int[0 to Inf] (4*Pi*r*(r*V(r)+Zion))
+     rchrg is the core charge radius for additional core charge used to
+      match the xc contribution to the hardness matrix
+     fchrg is the prefactor of the core charge expression
+     qchrg is the total (integrated) core charge
+Following the header are, for l=0 to lmax, the pseudopotentials
+in the form of a title line followed by 667 lines of data, each line
+containing three numbers so that the radial grid values from 0 to 2000
+are given.  The title line gives the value of l first followed by some
+text.  For the case of Si, e.g., for l=0, this line is
+=l for Teter pseudopotential
+followed by the 667 lines, 3 numbers each, giving the l=0
+potential on the radial grid described above.
+Following the pseudopotentials are the first projection functions,
+again given for each l with a title line followed by 667 data lines.
+Following the first projection functions for each l are the second
+projection functions, if any (determined by nproj).
+Following the second projection functions, if any, are several lines
+of additional data which is not read by plane_wave but is provided
+to describe more about the details of the construction of the
+pseudopotential.  Omission of these lines does not affect the running
+of plane_wave (at this time).
+If you do not wish to use core charges, simply set fchrg to 0 and
+use rchrg=1, qchrg=0.
+If you wish to make a local potential, use lmax=lloc=0, nproj=0, and
+you need not provide any projection function(s) (at this time).
+The values of rms, ekb1, ekb2, epsatm, e99.0, e99.9 are used only
+for information (at this time) so may be set to 0 when creating
+a pseudopotential file.  rcpsp is still used as the definition of the
+pseudopotential core radius so it must be provided.
+To best understand this data structure, it is recommended to study
+several pseudopotential files and compare their contents with the
+description given here.
+Inside ABINIT, a pseudopotential with format 1 will be treated by
+the routine psp1in.f, that calls psp1lo.f (local part),
+psp1nl.f (non-local part), and psp1cc.f (XC core correction).
+As a matter of numerical accuracy, note that the integral
+of (V(r)+Zion/r) r^2 in psp1lo.f is performed from 0 to the highest
+allowed radius (usually about 100 a.u.), without cut-off.
+V(r)+Zion/r should tend rapidly to zero
+for large radii (beyond 5 a.u.), but this correct behaviour will
+not be enforced by the routine. If the tail of V(r) is inaccurate
+(i.e. if the pseudopotential is in single precision), there
+will be large inaccuracies in the integral, because of the r^2 factor.