CASTEP > Dialogs in CASTEP > CASTEP Calculation dialog > Properties tab > Core level spectroscopy selection > CASTEP Core Level Spectroscopy Options dialog

CASTEP Core Level Spectroscopy Options dialog

The CASTEP Core Level Spectroscopy Options dialog allows you to specify the density of the k-point set and the eigenvalue convergence criterion used for core level spectra calculations.

The Monkhorst-Pack k-point grid to be used in the calculation can be specified in one of four ways:

Gamma point only: When selected, indicates that a single k-point at (0,0,0) will be used for the density of states calculation.

Quality: When selected, indicates that the k-point grid will be generated using a k-point separation appropriate to the specified quality level. Select the desired quality level from the dropdown list. Available options are:

The k-point separations associated with the three Quality settings are as follows:

Quality k-point separation (Å-1)
Coarse 0.07
Medium 0.05
Fine 0.04

Separation: When selected, indicates that the k-point grid will be generated according to the specified k-point separation. Specify the k-point separation, in Å-1, in the associated text box.

When the Separation option is selected, the Monkhorst-Pack parameters are derived to give the specified separation between neighboring grid points.

Custom grid parameters: When selected, indicates that the k-point grid will be generated using the Monkhorst-Pack grid parameters and the origin shift in fractional reciprocal space coordinates specified in the Grid parameters and Origin shift text boxes, respectively.

Grid parameters: Specify the Monkhorst-Pack grid parameters in each of the lattice directions.

Actual spacing: Displays the k-point separation, in Å-1, resulting from the currently specified Monkhorst-Pack grid parameters in each of the lattice directions.

Origin shift: Specify the offset of the Monkhorst-Pack grid in fractional reciprocal space coordinates.

The Grid parameters and Origin shift controls are enabled only if the Custom grid parameters option is selected.

Display points...: Displays the number and fractional coordinates of the reciprocal space mesh points that would be generated using the currently specified parameters.

The actual set of k-points that will be used in the calculations may be altered if the symmetry of the system changes.

Band energy tolerance: Specify the convergence criterion in eV for electronic eigenvalues during the core level spectroscopy calculation. The calculation will stop when all electronic eigenvalues change by less than this value over a single iteration of the electronic structure.

Help: Displays this Help topic.

Access methods

Menu Modules | CASTEP | Calculation | Properties | Core level spectroscopy | More...
Toolbar | Calculation | Properties | Core level spectroscopy | More...
See Also:

Properties tab - CASTEP Calculation dialog

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