Dear all,
I am working with GSAS for structure refinement. I am new in the field. So I
probably have some silly questions. When I introduce anisotropic thermal
parameters (U11, U22, ... U23) some of them are negative. Is this possible?
Should I always refine U12, U13 and U23? I used the third peak profile
function to describe the peak shape. I introduced Lorentzian microstrain
(L11, L22, ... L23) in my sample (this improved the fit substantially).
However, some of the Lij are negative. Is this possible?
With best regards,
Richard Bruls
