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how_to_prepare_the_new_tip_and_sample_for_stm_simulations [2009/11/25 15:32] vroz |
how_to_prepare_the_new_tip_and_sample_for_stm_simulations [2011/02/18 13:13] (current) |
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- | ==== I. The geometry ==== | + | ==== The geometry ==== |
First of all we need the “*.bas” file of the tip and sample geometry | First of all we need the “*.bas” file of the tip and sample geometry | ||
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- | ==== II. The files we need ==== | + | ==== The files we need ==== |
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this script). | this script). | ||
- | == I.II.I. The “run_hops.com” script: == | + | == II.II.I. The “run_hops.com” script: == |
#!/bin/bash \\ | #!/bin/bash \\ | ||
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rm -f tip_sample_aux | rm -f tip_sample_aux | ||
- | == I.II.II. The “README” file: == | + | == II.II.II. The “README” file: == |
a short description how to generate hopping data \\ | a short description how to generate hopping data \\ | ||
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and d 2, the interaction pi will be 1 and delta 2. \\ | and d 2, the interaction pi will be 1 and delta 2. \\ | ||
For long distances, we do the parallel planes approximation using | For long distances, we do the parallel planes approximation using | ||
- | the expression: | + | the expression: \\ |
- | **A.e<sup>-W.r</sup>** | + | A.e<sup>-W.r</sup> |
- | The A (4th value in the row) is the independent value we | + | The "A" (4th value in the row) is the independent value we |
- | have to find. α (5th value) depends on the orbitals you have in the hoppings, the | + | have to find. "α" (5th value) depends on the orbitals you have in the hoppings, the |
expression used is: α=l1+l2+1, but sometimes it could be changed depending on | expression used is: α=l1+l2+1, but sometimes it could be changed depending on | ||
- | the fix conditions. The W (6th) is related with the work function of the | + | the fix conditions. The "W" (6th) is related with the work function of the |
materials in the hopping: | materials in the hopping: | ||
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7th and 8th values in the row are related with the simple basis or double basis | 7th and 8th values in the row are related with the simple basis or double basis | ||
case. When you have a double basis you need an extra parameter to differentiate | case. When you have a double basis you need an extra parameter to differentiate | ||
- | from the simple basis orbital. The last value is the cut‐off radius. | + | from the simple basis orbital. \\ |
+ | The last value is the cut‐off radius. | ||
- | \\ | + | Here you can download : \\ |
+ | ========================. \\ | ||
+ | ="run_hops.com" script \\ | ||
+ | ="README" file \\ | ||
+ | ========================. | ||
- | ==== II.III. tip_g_str.inp ==== | + | \\ |
+ | |||
+ | === II.III. tip_g_str.inp === | ||
Last thing which we have to do is to write the “tip_g_str.inp” file. This 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 | 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 | 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: | + | 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 5 ! natoms_tip_contributing, natoms_tip \\ |
- | 1.590800 1.590800 1.590800 1 9 ! x, y, z, atomic type, # of orbitals | + | 0.000000 0.000000 0.400000 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 1.590800 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 | + | ‐1.590800 1.59080 1.59080 1 9 ! x, y, z, atomic type, # of orbitals \\ |
- | 3 ! number of shells in each type of atom | + | ‐1.590800 ‐1.59080 1.59080 1 9 ! x, y, z, atomic type, # of orbitals \\ |
- | 0 1 2 ! l for each shell in atom type=1 | + | 3 ! number of shells in each type of atom \\ |
- | ‐2.0 4.0 81 ! energy initial, range and steps in dos file | + | 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)// |