# 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.

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 or if you want to compute some post-SCF properties (e.g. the DOS or the band structure). Similarly, a geometry optimization can be restarted with the subkey GeometryOptimization You can use the geometry of a previous calculation.

Some examples are available in the $ADFHOME/examples/band directory and are discussed in the Examples section. ## Restart key¶ Restart Tells the program that it should restart with the restart file. Restart File filename {option} UseDensityMatrix True/False End  File filename is the name of the restart file UseDensityMatrix If True, SCF the density matrix will be used. Requires you to set the “Save DensityMatrix” in the previous run. options is the program part to do a restart for: 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, NOCVOrbitalPlot 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 • s[rho] Reduced density gradient. Common ingredient for XC functionals • s[rho(fit)] Same as above, now for the fit density • alpha[rho] Ingredient for some meta-GGAs 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¶ NOCVOrbitalPlot (block-type) Goes together with the Restart%NOCVOrbitalPlot and Grid keys. See example PEDANOCV_MgO+CO. Example input ... Restart File my.runkf NOCVOrbitalPlot End Grid Type Coarse End NOCVOrbitalPlot 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 energy 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.

## Save¶

With “Save -something-” directives you can tell BAND to save extra information.

TAPE10 One option is “Save TAPE10”, which will cause the file with the grid to be saved.

DensityMatrix The “Save DensityMatrix” command causes the density matrix to be written to the RUNKF file, needed with Restart%UseDensityMatrix true.