CASTEP > Dialogs in CASTEP > CASTEP Calculation dialog > Properties tab > Phonons selection - Properties tab: CASTEP Calculation dialog

Checking the Phonons checkbox on the Properties tab displays options for calculating phonon properties.

Density of states: When checked, indicates that the phonon density of states will be computed as part of the CASTEP run.

Dispersion: When checked, indicates that the phonon dispersion will be computed as part of the CASTEP run.

Both: When selected both the phonon density of states and dispersion will be calculated during the CASTEP run.

Calculate LO-TO splitting: When checked, indicates that a non-analytical correction to the dynamical matrix will be applied. The LO-TO phonon frequency splitting at the Γ-point will be calculated along the directions connecting the Γ-point with the neighboring points along the reciprocal space path. Default = checked.

Method: Select the technique to be used to calculate phonon frequencies from the dropdown list. Available options are:

- Linear response
- Finite displacement

Finite displacement phonons are available only at the commensurate q-points (at the cost of creating a supercell). However, in this case, the phonon frequencies can be obtained with no limitations on the settings or the physical properties of the system. The finite displacement technique can be used for metals, ultrasoft potentials, spin-polarized systems, and so on.

If LO-TO splitting is requested, then the restrictions on the system type and settings (insulator, norm-conserving potentials, non-spin-polarized calculation) are the same for both the linear response and finite displacement techniques.

More...: Provides access to the CASTEP Phonon Properties Setup dialog, which allows you to set additional parameters affecting a phonon calculation, including the convergence tolerance.

Access methods

Menu | Modules | CASTEP | Calculation | Properties | Phonons |

Toolbar | | Calculation | Properties | Phonons |

Properties tab - CASTEP Calculation dialog

Requesting vibrational properties

Phonons

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