john201004 How do I know that the refined beq and ADPs is reasonable for my atom? Or in other words how do I know the reasonable range of these parameters? Once I was tolled by my colleague that they shouldn't be neither zero nor one, but when look at examples on Topas manual I found that in certain examples the value is given higher than one? So I am bit confused please some body will help me to explain it? Thank you in advance. Sincerely
ahhill If you are used to GSAS Uiso values, then, the following link will be useful. http://topas.dur.ac.uk/unb/forum.php?req=thread&id=25
rowlesmr They shouldn't be zero, as it implies there is no atom there. Neither should they be negative, as that means that the intensity corrections that you're using are wrong, and you're actually taking away intensity by using a "neagative" scattering atom. As to the actual value, the answer is "it depends", but I can't ever remember using a value greater than ~3.