CASTEP > Tasks in CASTEP > Setting up CASTEP calculations > Requesting electronic, structural, and vibrational properties > Requesting density of states

Requesting density of states

Calculating densities of states produces electronic energies on the Monkhorst-Pack mesh of k-points. CASTEP can always produce a density of states plot, based simply on the results of the main self-consistent run. The purpose of a density of states property run is typically to:

Such calculations are intended to provide a better quality density of states over a larger energy range.

This type of run can be also used to request a partial density of states. The quality of the k-points set is controlled by the k-point set dropdown list on the Properties tab on the Calculation dialog. Conduction band states can be included by specifying a nonzero value in the Empty bands text box on the same tab.

You are not required to use the same exchange-correlation functional in the density of states calculation as in the main calculation. This allows you to select a nonlocal screened-exchange functional to study the electronic structure after performing, for example geometry optimization with a variable cell using the GGA functional.

CASTEP does not support the use of nonlocal functionals (screened exchange, exact exchange, etc.) for ultrasoft pseudopotentials, i.e., nonlocal functionals can only be requested if all the pseudopotentials for the calculation are specified as norm-conserving.

To obtain representative density of states it is recommended to use a k-point set which is either the same or finer quality than the one used in the SCF calculations.

To calculate density of states

  1. Choose Modules | CASTEP | Calculation from the Materials Studio menu bar.
  2. Select the Properties tab.
  3. Check the Density of states option on the properties list.
  4. If necessary, modify the Number of empty bands to include more or less states in the conduction band.
  5. Optionally, adjust the density of Monkhorst-Pack k-points used for the density of states calculation by using k-point set dropdown list.
  6. If you would like to generate partial or local densities of states, check Calculate PDOS.
  7. Click the More... button to open the CASTEP Density of States Options dialog. This dialog gives you complete control over setting up the Monkhorst-Pack grid.
  8. Check Use separate XC functional for DOS calculation on the CASTEP Density of States Options dialog if you want to use, for example, a nonlocal functional for the electronic structure calculation.
  9. Select the alternative Functional you wish to use from the dropdown list on the same dialog.
See Also:

Mulliken population analysis
Hirshfeld charge analysis
Phonon density of states
Density of states and partial density of states
Optical properties
CASTEP Calculation dialog

Accelrys Materials Studio 8.0 Help: Wednesday, December 17, 2014
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