CASTEP Phonon Density of States Options dialog
The CASTEP Phonon Density of States Options dialog allows you to specify the q-vector set for phonon density of states calculations.
The Monkhorst-Pack q-vector grid to be used in the calculation can be specified in one of four ways.
The option selected here propagates from the Quality setting in the Density of States section on the CASTEP Phonon Properties Setup dialog. As a result, altering the selection here will also change the setting on the CASTEP Phonon Properties Options dialog.
Gamma point only: When selected, indicates that a single q-vector at (0,0,0) will be used for the density of states calculation.
Quality: When selected, indicates that the q-vector grid will be generated using a q-vector separation appropriate to the specified quality level. Select the desired quality level from the dropdown list. Available options and the associated q-vector separations are:
| Quality | k-point separation (Å-1) |
|---|---|
| Coarse | 0.07 |
| Medium | 0.05 |
| Fine | 0.04 |
Separation: When selected, indicates that the q-vector grid will be generated according to the specified q-vector separation. Specify the q-vector separation, in Å-1, in the associated text box.
When the Separation option is selected, the Monkhorst-Pack parameters are derived so as to produce the specified separation between neighboring grid points.
Custom grid parameters: When selected, indicates that the q-vector 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 you select the Custom grid parameters option.
Display points...: Displays, in a new window, the number and fractional coordinates of the reciprocal space mesh points that would be generated using the currently specified parameters.
The actual set of q-vectors that will be used in the calculation may be altered if the symmetry of the system changes.
Help: Displays
Access methods
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