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CO absorption on a Cu slab

Sample directory: band/e_Frags_COCu/

This example illustrates the usage of fragments in a BAND calculation, for analysis purposes. The setup involves first the computation of the free CO overlayer, which is to be absorbed on a Cu surface. To suppress (most of the) interactions between the CO molecules, i.e. to effectively get the molecular CO, the KSpace parameter is set to 1 (= no dispersion), and the lattice parameters are set so large that the CO molecules are far apart.

The RUNKF key is used to save the standard result file, under the name 't21.CO'.

$ADFBIN/band << eor




O fragment

Comment
 Technical  
   Zero order k space integration
   Good real space integration accuracy
   Definitions of variables
 Features
   Lattice   : 2D, large lattice vectors
   Unit cell : 2 atoms, 1x1, quasi molecular
   Basis     : NO+STO w/ core
   Options   : Save RUNKF restart (fragment) file
               Prepare fragment for follow up
End

MAXMEMORYUSAGE 40

Save RUNKF  ! save RUNKF as fragment file

Basis
 PrepareFragment  ! keep all bands, not only the occupied ones
End

PRINT EIGENS

Kspace   1  ! neglect dispersion
Accuracy   4

Define
  bond=2.18
  far=25
End

Lattice     ! CO molecules far apart
  far  0.0
  0.0  far
End

Atoms   C
  0 0 0
End

Atoms   O
  0 0 bond
End

....
End Input
eor

mv RUNKF t21.CO

the fragment(s) to use: the file (t21.CO) and the numbering of atoms on the fragment file versus their occurrence in this calculation.

With FragLabels we assign names to the different symmetry orbitals.

The Density-of-States analysis details are given with the keys DOS (energy grid, result file with DOS data) and, optionally, GrossPopulations and OverlapPopulations.

$ADFBIN/band << eor
Title Cu slab with CO adsorbed

Comment
 Technical  
   Quadratic K space integration (low)
   Good real space integration accuracy
   Definitions of variables
 Features
   Lattice   : 2D
   Unit cell : 3 atoms, 1x1
   Basis     : NO+STO w/ core
   Options   : Molecular fragment
               Analysis: DOS, PDOS, COOP
End        

MaxMemoryUsage 40

Kspace 3
Accuracy 4


! fragment options

Basis
 SimpleFrag
End

NATOMSASFRAGMENT 2

Fragments t21.CO
  1 1
  2 2
End

Fragmentlabels
  2Sigma
  2Sigma*
  1Pi_x
  1Pi_y
  3Sigma
  1Pi_x*
  1Pi_y*
  3Sigma*
End

DOS   ! Analysis
  FILE  pdos.CO_Cu
  ENERGIES 500
  MIN -0.750
  MAX 0.300
End

GROSSPOPULATIONS
  3 2    ! All metal d states
  SUM     ! ALl metal sp states
    3 0
    3 1
  ENDSUM

  FRAG 1   ! All CO states
  SUM   ! CO 1pi
    FRAGFUN 1 5
    FRAGFUN 1 6
  ENDSUM
  FRAGFUN 1 7  ! CO 5-sigma
End

OVERLAPPOPULATIONS
  LEFT   ! Metal d with CO
    3 2
  RIGHT
    FRAG 1
End

Define
  dist=3.44
  bond=2.18
End

Lattice
  4.822 0.0
  0.0   4.822
End

Atoms   C
  0 0 dist
End

Atoms   O
  0 0 dist+bond
End

Atoms   CU
  0.0   0.0   0.0
End

...

End Input
eor

Finally, we copy the computed DOS data from the DOS result file to standard output.

echo Contents of DOS file
cat pdos.CO_Cu