I noted with interest that with the release of Materials Studio 7, CASTEP could now calculate excited state effects.  I was surprised, however, about the lack of documentation regarding the implementation.  Is it fair to assume that the Casida approach is implemented and that one needs a discrete level system (e.g. finite extent)? Assuming this to be true, I tried a small cluster of GeTe from a carefully converged ground state structure, but found that the TDDFT calculation did not converge in the 50 default interations allowed.  It would appear that the front end is rather limited in its options which leads me to my question.  Where can I find an exaustive list of the keywords for the cell and parameter CASTEP input files regarding a TDDFT calculation?  Is there any more extensive documentation planned or even better already available?  If such documentation is available already, I apologize for not finding it myself and would appreciate hearing of appropriate links or examples.

Best wishes,

                      Paul Fons