The tip_e_str.inp file
The “tip_e_str.inp” file contains informations about the density of states of the tip. Than we need to run the FIREBALL code with the following settings of “fireball.in” file:
&OPTION part
‐ basisfile = <filename>
‐ lvsfile = <filename>
‐ kptpreference = <filename>
‐ nstepf = 1
- ifixcharge= 1
&OUTPUT part
- iwrtdos = 1
For running the DOS computation we need even “dos.optional” file with the DOS settings. The file could looks like this:
1.0 ! scale factor of coord 1 5 ! natom_beg, natom_end for dos calculation 41 ! number of energy steps -3.8 0.05 ! first energy and step for dos calculation 1 ! 1/0 yes/no write the tip_e_str.inp -3.5 -2.0 ! minimun and maximum energies for the writting the tip 0.05 ! (eta) imaginary part for green functionin calculation
The result is list of files with the densities and charges of single atoms of the tip (1-5) and the “tip_e_str.inp file”
The tip_g_str.inp file
Last thing which we have to do is to write the “tip_g_str.inp” file. This file
contains the geometrical structure of the tip. The xyz atom coordinates should be
written there at the same order as we used for the “tip_e_str.inp” file, with the
apex atom at first position. The file could looks like this:
1 5 ! natoms_tip_contributing, natoms_tip 0.000000 0.000000 0.400000 1 9 ! x, y, z, atomic type, # of orbitals 1.590800 1.590800 1.590800 1 9 ! x, y, z, atomic type, # of orbitals 1.590800 ‐1.59080 1.59080 1 9 ! x, y, z, atomic type, # of orbitals ‐1.590800 1.59080 1.59080 1 9 ! x, y, z, atomic type, # of orbitals ‐1.590800 ‐1.59080 1.59080 1 9 ! x, y, z, atomic type, # of orbitals 3 ! number of shells in each type of atom 0 1 2 ! l for each shell in atom type=1 ‐2.0 4.0 81 ! energy initial, range and steps in dos file
But be carefull, the energy in the STM code is related to the Fermi level. When Fermi level is -2 eV from FIREBALL in the “tip_g_str.inp” in it's last line the first value has to be 0.0 (energy initial - Fermi level)
