Of course you can. There is an option "fix specific reciprocal metric tensor elements" - that's what you need. It is located in "least-squares refinement set-up/overall parameters/lattice parameters" in GSAS menu.
It seems that it is not accessible via EXPGUI interface. Sincerely, Maxim. -----Original Message----- From: prasu...@veccal.ernet.in [mailto:prasu...@veccal.ernet.in] Sent: Monday, September 14, 2009 4:45 PM To: Rietveld Method; Robert Von Dreele (vondreel) Subject: refining the structural parameters selectively Dear all, Using triclinic structure(P1) in GSAS, how can i refine the lattice parameters only and make the angles fixed? In the phase tab, i am getting only the refine cell option, which refines a,b,c,alpha,beta,gamma alltogether. Is there any technique to refine only one or a fiew of them selectively? Thanking you, With regards, Prasun Sharma Chowdhury SRF, VECC Kolkata - 700064 West Bengal India