Density of States (DOS)

DOS
   CalcDOS Yes/No
   CalcPDOS Yes/No
   CalcPopulationAnalysis Yes/No
   CompensateDeltaE Yes/No
   DeltaE float
   Energies integer
   File string
   IntegrateDeltaE Yes/No
   Max float
   Min float
   StoreCoopPerBasPair Yes/No
End
DOS
Type:

Block

Description:

Density-Of-States (DOS) options

CalcDOS
Type:

Bool

Default value:

Yes

GUI name:

Calculate DOS

Description:

Whether or not to calculate the density of states.

CalcPDOS
Type:

Bool

Default value:

No

GUI name:

Calculate PDOS

Description:

Whether or not to calculate the partial DOS (projections on basis functions). This can be significantly more expensive than calculating the total DOS

CalcPopulationAnalysis
Type:

Bool

Default value:

Yes

GUI name:

Calculate Mulliken charges

Description:

Whether or not to calculate the population analysis. Population analysis can become very expensive when there are many symmetry operators, such as in a super cell.

CompensateDeltaE
Type:

Bool

Default value:

Yes

Description:

Only relevant when IntegrateDeltaE=yes. If set to true then after integrating each interval over DeltaE the result is divided by DeltaE, so that the unit is DOS.

DeltaE
Type:

Float

Default value:

0.005

Unit:

Hartree

GUI name:

Delta E

Description:

Energy step for the DOS grid. Using a smaller value (e.g. half the default value) will result in a finer sampling of the DOS.

Energies
Type:

Integer

Description:

Number of equidistant energy-values for the DOS grid. This keyword is superseded by the ‘DeltaE’ keyword.

File
Type:

String

Description:

Write the DOS (plain text format) to the specified file instead of writing it to the standard output.

IntegrateDeltaE
Type:

Bool

Default value:

Yes

Description:

This subkey handles which algorithm is used to calculate the data-points in the plotted DOS. If true, the data-points represent an integral over the states in an energy interval. Here, the energy interval depends on the number of Energies and the user-defined upper and lower energy for the calculation of the DOS. The result has as unit [number of states / (energy interval * unit cell)]. If false, the data-points do represent the number of states for a specific energy and the resulting plot is equal to the DOS per unit cell (unit: [1/energy]). Since the resulting plot can be a wild function and one might miss features of the DOS due to the step length between the energies, the default is set to the integration algorithm.

Max
Type:

Float

Unit:

Hartree

Description:

User defined upper bound energy (with respect to the Fermi energy)

Min
Type:

Float

Unit:

Hartree

Description:

User defined lower bound energy (with respect to the Fermi energy)

StoreCoopPerBasPair
Type:

Bool

Default value:

No

GUI name:

Calculate COOP

Description:

Calculate the COOP (crystal orbital overlap population).

An example input:

DOS
   Enabled     True
   Energies    500
   Min        -0.35
   Max         1.05
   File        plotfile
End

According to this example, DOS values will be generated in an equidistant mesh of 500 energy values, ranging from 0.35 a.u. below the Fermi level to 1.05 a.u. above it. All information will be written to a file plotfile. The information on the plot file is a long list of pairs of values (energy and DOS), with some informative text-headers and general information. DOS values are generated for the total DOS and optionally also for some partial DOS (see the keys GrossPopulations and OverlapPopulations).

A common problem is that of missing DOS: an energy interval with bands but no DOS. This is caused by an insufficient k-space sampling. Try to Restart the DOS with a better k-grid.

In the DOS and Band Structure GUI modules, it is possible to visualize partial density of states (p-DOS). The partial contributions are obtained from the total DOS by following the Mulliken population analysis partitioning prescription (see wikipedia).

Tip

The tutorial Calculation of Band Structure and COOP of CsPbBr3 with BAND contains some advanced usage of the DOS and BAND Structure GUI modules.

Gross populations

GrossPopulations # Non-standard block. See details.
   ...
End
GrossPopulations
Type:

Non-standard block

Description:

Partial DOS (pDOS) are generated for the gross populations listed under this key. See example.

Syntax:

GrossPopulations
   {iat lq}
   {FragFun jat ifun}
   {Frag kat}
   {Sum
    ...
    EndSum}
End
iat

pDOS is generated for atom lq.

FragFun

pDOS is generated for atom jat with all real spherical harmonics belonging to \(l\)-value ifun.

Frag

pDOS of the functions belonging to atom kat will be calculated.

Sum

sum all pDOS, specified in this block.

Example:

GrossPopulations
   FragFun 1 2:: Second function of first atom
   Frag 2 :: Sum of all functions from second atom
   SUM:: sum following PDOSes
      Frag 1::Atom nr.1
      FragFun 2 1::First function of second atom
      5 1:: All pfunctions of fifth atom
   EndSum
End

Overlap populations

OverlapPopulations # Non-standard block. See details.
   ...
End
OverlapPopulations
Type:

Non-standard block

Description:

Overlap population weighted DOS (OPWDOS), also known as the crystal orbital overlap population (COOP).

Overlap population weighted DOS are generated for the overlap populations listed:

OVERLAPPOPULATIONS
   Left
      { iat lq }
      { FragFun jat ifun }
      { Frag kat }
   Right
      ...
End

You can use this to get the OPWDOS of two functions, or, if you like, one bunch of functions with another bunch of functions. The key-block should consist of left-right pairs. After a line with left you enter lines that specify one or more functions (according to GrossPopulations), followed by a similar structure beginning with right, which will produce the OPWDOS of the left functions with the right functions.

Example:

OVERLAPPOPULATIONS
   LEFT::First OPWDOS
      Frag 1
   RIGHT
      Frag 2
   LEFT:: Next OPWDOS
      FragFun 1 1
   RIGHT
      2 1
      FragFun 3 5
End