Restarts

The main results of a BAND calculation are stored in the RUNKF file. If you save this file you can use it to restart your calculation. The input for the restart calculation is essentially the same, except for some extra keys, like Restart, Grid, and DensityPlot.

The DOS section that outputs information of the SCF solution can be executed with key Restart, subkey DOS and orbital plots can be obtained with subkey OrbitalPlot. Likewise, plots of the density (and many other symmetric properties) can can be obtained with the key DensityPlot. Density and orbital plot restarts require the specification of the Grid key. With the subkey SCF you can start the SCF procedure with the last solution from the restart file. This can be useful if the SCF did not converge. Also if you have changed some settings that should have little effect, like the integration accuracy, the restart SCF option can help you to save a few cycles. Similarly, a geometry optimization can be restarted with the subkey GeometryOptimization You can use the geometry of a previous calculation.

Restart key

Restart

Tells the program that it should restart with the restart file.

Restart
   File filename
   {option}
End

File

filename is the name of the restart file

options is the program part to do a restart for:

• SCF
• GeometryOptimization
• Geometry
• DOS
• OrbitalPlot
• DensityPlot
• NOCVdRhoPlot
• NOCVOrbsPlot

Usually the input for a restart is the same as for the original calculation, where you add some extra options.

Grid

Grid (block-type)

Used for restart options OrbitalPlot, DensityPlot, NOCVOrbsPlot and NOCVdRhoPlot. There are two ways to define your grid. The most easy way is to use the Type key which can have the values Coarse, Medium, and Fine, for example

Grid
   Type Coarse
End

This generates automatically a grid around the atoms in the unit cell. The alternative is to specify everything by hand. The following input would create a cube from (-1,-1,-1) to (1,1,1)

Grid
   -1 -1 -1 ! Starting point
   1 0 0 0.1   ! vec1 and dvec1
   0 1 0 0.1   ! vec2 and dvec2
   0 0 1 0.1   ! vec3 and dvec3
   20 20 20    ! nr. of steps along three directions
End

Plots of the density, potential, and many more properties

DensityPlot (block-type)

Goes together with the Restart%DensityPlot and Grid keys. Example input

...
Restart vi
   File my.runkf
   DensityPlot
End

Grid
   Type Coarse
End

DensityPlot
   rho(fit)
   vxc[rho]
End
...

After such a run you get a TAPE41 file that you should rename to my.t41, and view with adfview.

The most common properties to plot are:

• rho(fit) The fitted density.
• v(coulomb) The Coulomb potential.
• vxc[rho(fit)] the XC potential (using the fitted density)
• vxc[rho] XC potential of the exact density
• rho The density
• |gradRho| The norm of the gradient of the density
• tau The symmetric kinetic energy density
• LDOS The local density of states. (See LDOS key)
• elf[rho] The electron localization function

Some more specialized options are:

• rho(deformation/fit) the fitted deformation density
• rho(atoms) The density of the startup atoms
• v(coulomb/atoms) The Coulomb potential of the start density

In the BAND example directory there is the Frags_COCu example which shows how this can be used in combination with the Fragment key.

Orbital plots

OrbitalPlot (block-type)

Goes together with the Restart%OrbitalPlot and Grid keys. In the BAND example directory there is the Cu_slab example that shows how this can be used. Example input

...
Restart
   File my.runkf
   OrbitalPlot
End

Grid
   Type Coarse
End

OrbitalPlot
   1 Band 5 8  ! for k-point 1 plot bands 5 to 8
   5 Band 6    ! for k-point 5 plot band 6
   6 -0.2 +0.3 ! for k-point 6 plot bands between -0.2 and +0.3 a.u. w.r.t Fermi level
End
...

After such a run you get a TAPE41 file that you should rename to my.t41, and view with adfview.

NOCV Orbital Plots

NOCVOrbsPlot (block-type)

Goes together with the Restart%NOCVOrbsPlot and Grid keys. See example PEDANOCV_MgO+CO. Example input

...
Restart
   File my.runkf
   NOCVOrbsPlot
End

Grid
   Type Coarse
End

NOCVOrbsPlot
   1 Band 5 8 ! for k-point 1 plot NOCV Orbitals 5 to 8
End
...

After such a run you get a TAPE41 file that you should rename to my.t41, and view with adfview.

NOCV Deformation Density Plots

NOCVdRhoPlot (block-type)

Goes together with the Restart%NOCVdRhoPlot and Grid keys. See example PEDANOCV_MgO+CO. Example input

...
Restart
   File my.runkf
   NOCVdRhoPlot
End

Grid
   Type Coarse
End

NOCVdRhoPlot
   1 Band 5 8 ! for k-point 1 plot NOCV deformation densities 5 to 8
End
...

After such a run you get a TAPE41 file that you should rename to my.t41, and view with adfview.

LDOS (STM)

LDOS (block-type)

Local Density-Of-States information. This can be used to generate STM images in the Tersoff-Hamann approximation.[35]

LDOS
   { Shift eshift }
   { DeltaNeg deneg }
   { DeltaPos depos }
End

Shift

(Default: 0.0 a.u.) The energy bias with respect to the fermi level in a.u..

DeltaNeg

(Default: 1e-4 a.u.) defines the lower bound energy as eshift-deneg.

DeltaPos

(Default: 1e-4 a.u.) defines the upper bound energz as eshift+depos.

The local density of states is integrated over the resulting interval. Example of an LDOS restart

Restart
   File my.runkf
   DensityPlot
End

Grid
   Type Coarse
End

DensityPlot
   LDOS
   Shift      0.1
   DeltaNeg .001
   DeltaPos 0
End

According to this example, we restart from the result file of a previous calculation. The calculation will generate a file TAPE41 which can be viewed with adfview. (Rename the file to my.t41)

See also Restart, and DensityPlot.

Complete example scripts for visualization

Below follows a complete example how to use BAND for visualizing. We start with the normal calculation for e.g. a Li slab

#!/bin/sh
# Contents of the file LiSlab.job

"$ADFBIN/band" << eor
TITLE Li Slab

UNITS
    length Angstrom
    angle Degree
END

ATOMS Li
   Li  0.0    0.0    0.0
   Li -1.745 -1.745 -1.745
END

Lattice
   3.49 0.000000 0
   0.000000 3.49 0
End

BasisDefaults
   BasisType DZ
   Core Large
End

XC
   LDA SCF VWN
END

end input
eor

# store the result file
mv RUNKF LiSlab.runkf

Note that we store the result file in “LiSlab.runkf”. In the next run we use this file to generate the plot file. The job is essentially a copy of the first job with some extra lines. In this case we instruct the program to generate plot information for the density and the LDOS

#!/bin/sh
# Contents of the file LiSlab_restart.job

"$ADFBIN/band" << eor
TITLE Li Slab

UNITS
    length Angstrom
    angle Degree
END

Restart
   File LiSlab.runkf
   DensityPlot
End

Grid
   Type Coarse
End

DensityPlot
   rho(fit)
   LDOS
End

LDOS
   shift 0.0
End

ATOMS
   Li  0.0    0.0    0.0
   Li -1.745 -1.745 -1.745
END

Lattice
   3.49 0.000000 0
   0.000000 3.49 0
End

BasisDefaults
   BasisType DZ
   Core Large
End

XC
   LDA SCF VWN
END

end input
eor

# Store the result file, and more importantly, the plot file (.t41)
mv RUNKF LiSlab_restart.runkf
mv TAPE41 LiSlab.t41

And then you can visualize the result with adfview.

$ADFBIN/adfview  LiSlab.runkf

It is most convenient to start adfview from the .runkf file rather than from the .t41.