I have been using GULP 4.0 for a long time for geometry and phonon calculations on semiconductor nanocrystals (“clusters”). I had to modify the source code for the subroutine deffreq to normalize the eigenvectors appropriately and to print out the reduced masses I need for further calculations. I’m now trying to switch to GULP 6.0 but the comments in the new deffreq routine indicate that clusters are not handled by that routine. I can’t figure out where these calculations are done for clusters. Can anyone enlighten me?