Nanosurf Lab

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==== 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"

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==== 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)//
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