Installation and general information

The distribution file archive (e.g. lev00_2.44.tgz) should be untarred and unzipped, e.g.

tar  -xzf  lev00_2.44.tgz

in a directory of your choice (e.g. /TOOLS).

lev00 code has to be compiled for every new system/application (contrary to tetr). This is because it requires much more memory (e.g. electron density on a grid) and is written in f77^3.4.

Before compiling the code for the first time, you should edit the script lev00.comp (supplied in subdirectory /TOOLS/SCRIPTS) to indicate the correct directory for the source code by setting the variable road there, e.g.

set road="/TOOLS"

The compilation of lev00 is performed by calling the script lev00.comp from your working directory (where is your VASP or SIESTA job resides). What is needed is the file param.inc file containing the parameters of your system:

• NGX,NGY,NGZ - the grid for the electron density files
• NSPEC - number of species
• NIONS - total number of atoms in the cell
• NKPTS - number of $\mathbf{k}$-points
• NBANDS - total number of ``bands'' (i.e. the states for each $\mathbf{k}$-point)
• ispin - equal 2 for spin-polarised calculations, equal to 1 otherwise.

This file can be created manually for each DFT job you are working with by using the Fortran parameter statements. In the cases of VASP and SIESTA, special routines are supplied to do this and some other necessary preparatory work for lev00 to work properly (see Sections 4 and 5). The old CASTEP has this file already. This is an example:

parameter (NGX= 60,NGY= 60,NGZ= 60)

parameter (NSPEC= 2,NIONS= 3)

parameter (NKPTS= 1,NBANDS= 8)

parameter (NPLWV=NGX*NGY*NGZ)

parameter (ispin= 1)

The script copies the file param.inc into the directory where the source code resides (variable $road in the script), compiles the code, and then moves it back to your current (working) directory. After running the script, you should find an executable lev00 there.

In practice, what you should do depends on the code you intend to use, and this will be described in the proper Sections 4, 5 and 6 for the VASP, SIESTA and CASTEP codes, respectively.