Dear Jane, the information in your email seems a little sparse. If you want to calculate the orientation/ angle or anything similar of two domains you have to define an appropriate coordinate system and the zero-point. The probably depends on what domains you are talking about - maybe I missed something. Tim -- Tim Gruene Institut fuer anorganische Chemie Tammannstr. 4 D-37077 Goettingen GPG Key ID = A46BEE1A On Fri, 19 Feb 2010, Jane Bailey wrote: > Dear all, > > Problem is coming one after another. I got another question about how to > calculate the domain/domain orientations (tilt and twist angles). Sorry I > probably disturb a bit often .... > > I searched a lot, but no publication says how it was calculated. Does anybody > know anything about this? > > Thanks a lot! > > Jane >