Nan, You haven't quite given me enough information to actually help. In this case, I'd need to see the crystallographic reference, or at least the input data, for the problem at hand. This is point #5 at http://cars9.uchicago.edu/~ravel/software/bugs.html. B -- Bruce Ravel ----------------------------------- bravel@bnl.gov My homepage: http://cars9.uchicago.edu/~ravel EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/ -----Original Message----- From: Nan Jiang [mailto:Nan.Jiang@asu.edu] Sent: Tue 10/9/2007 5:59 PM To: bravel@anl.gov Subject: space group C-1 Dear Dr Ravel I use Atoms to generate clusters for FEFF calculations. My space group is C-1, which is not included in your table. I tried to use P-1 instead, but it does not work properly. There are four symmetries in C-4, but only 2 in P-1. Could you advise me on this? Thanks for your time. Nan Jiang