Re: GSAS thermal parameters and peak profile

[Peter Y. Zavalij]

I do not know bout Lij but Uij can be negative -- However only when "i" is not equal 
"j".
Uii should be positive and greater than 0 to make physical sense. Moreover,
there are other restrictions too and I can find them if you are interested.

Dr. Peter Y. Zavalij    University Crystallographer
   Materials Research Center, SUNY at Binghamton
Ph/Fax:(607)777-4623  E-mail:[EMAIL PROTECTED]
http://imr.chem.binghamton.edu/zavalij/zavalij.html