We start by preparing an inputcard file Use OPTION 'full inv'. Set the ALATBASIS=6.76d0, LMAX=3, NATYP=1, the BRAVAIS vectors for fcc, RBASIS is the zero vector, INTERFACE=.FALSE. since we are doing a 3d calculation, RCLUSTZ, RCLUSTXY should be set the same, a bigger value increases the size of the TB-cluster thus increasing computer time. A value 1.1 should be ok for this test (first and second neighbors). ATOMINFO needs the atomic number say 29.00 for Cu, the core configuration, 1 3 3 0 0, for 1s,2s,3s,2p,3p core CLS is 1, REFPOT is also 1, NTC is 1, IRNS is 1 if ASA and is usually set to 278 for FP. RMT plays no role in ASA but should be set correctly for Full potential, the program voronoi helps to decide on this. WEIGHT is usually set to 1.0 but if the basis has more than one atoms then it could be set to a different value. The bigger the weight the bigger the cell of the atom.
After this we need an energy contour for the valence integration, the voronoi program helps to decide where to start the energy contour which ends usually at the Fermi level. A rectangular contour in used with temperature so usual values are EMIN=-0.4 the correct value depends on the system and is suggested by the voronoi program. EMAX=1.d0, this value is usually ignored during self consistency, the EMAX that apears in the potential is used instead. EMAX is used in case of DOS calculation. NPOL=5 (usually), NPT1=3, NPT2=20, NPT3=3, are typical values. The number of points for BZ integration BZDIVIDE= 30 30 30 (for x,y,z directions). Then we have the self consistency parameters, the filenames used , and finally the Ewald sum parameters typically RMAX=6.0d0, GMAX=60.0d0.
If the inputcard is prepared with the help of the examples in the end we are ready to prepare potentials.
Next step is to run the voronoi program which we will briefly describe. The purpose of the voronoi program is to divide space in atomic cells, make ASA construction, prepare potentials, prepare shape functions, and interpolate from one radial mesh to another. Input is the Bravais, and basis lattice vectors, as well as the atomic numbers for each atomic cite, moreover the size of each atom is controlled by the WEIGHT and in case of FP the RMT should be set correctly. Output includes information about the lattice, like volume, atomic volumes, muffin-tin spheres, information about atomic polyhedra, faces etc. Visualization of the lattice is possible using RASMOL, or POVRAY. Moreover the program uses a database of potentials to produce the potential in the desired radial mesh. Almost all elements are included except the lanthanides and actinides, in the current database, which will be extended in the future. Important is that the position of the core states are printed out so that we can decide on the valence energy contour required for each particular system. The potential output.pot will be produced if the filename of the potential file is left blank in the inputcard. If a filename appears there the program will try to use it as starting potential, BUT it must be in a special format (look running option GENPOT).
Using the output of the voronoi program we can decide on the radius of the repulsive potential (usually 4 Rydberg high) we should use to obtain screening. Criterion is that repulsive potentials should not overlap, and they should fill space as much as possible. If we decide on the radius of the repulsive potential use the small utility (Conshift.f) to prepare 4Ryshift files. This will be included in the programs in future versions.
If we have the potential (output.pot), the 4Ryshift file, the lebedev file, we must create a directory called "mesh" and we can run the SKKR program, and obtain the self-consistent potential.
The only problem is the correct setting of the parameters for the program compilation, this is important since currently the code is on FORTRAN77 so changing the number of atoms requires usually recompilation. The parameters are explained in section 12 "Parameters of the SKKR", you might also have a look at the part "compiling the programs". For DOS and band-structure look at the relevant sections later in this manual.