When a CASTEP calculation returns a Hessian (dynamical matrix) at the Γ-point, then vibrational frequencies for the bonds in the system being studied can be calculated and visualized using the Vibrational Analysis tool.
After a CASTEP job that included calculation of the electric field response (i.e., the Polarizability, IR and Raman spectra checkbox was checked on the Properties tab of the CASTEP Calculation dialog) is complete and the results files have been downloaded successfully, Materials Studio will automatically import the Hessian matrix, provided that the CASTEP job was not a Properties run.
A dynamical matrix is returned if the TASK keyword in the input parameters (
is set to either Efield or Phonon+Efield and there is a Γ-point among the phonon
k-vectors. You can achieve this either by checking the Polarizability, IR and Raman spectra checkbox on the
Properties tab of the CASTEP Calculation dialog or, alternatively, if you wish to
calculate the phonon dispersion or phonon density of states, by checking the Phonons checkbox in the list on the
Properties tab, checking the Dispersion or Density of states checkboxes,
as appropriate, that appear below the list, and ensuring that there is a Γ-point in the q-vector set.
In order to carry out a vibrational analysis, you will need to import a Hessian matrix from the output of a CASTEP run.
To import a Hessian and display an IR spectrum
If you requested that the electric field response be calculated as part of the CASTEP job by checking the Polarizability, IR and Raman spectra checkbox on the Properties tab of the CASTEP Calculation dialog, you will be able to display vibrational mode frequencies and absorption intensities for the structure being studied in the form of a list of values or graphically as a vibrational spectrum using the Vibrational Analysis tool.
To display a Raman spectrum
seedname Raman.xcd, is created in the results folder.
Analyzing CASTEP results
Requesting vibrational properties
Requesting electric field response