recently it was pointed out (J. Appl. Cryst. 37 (2004) 123-135) that the approach proposed by Von Dreele can have indeed - under certain circumstances and restrictions to the parameters - a physical meaning, e.g. concentration fluctuations can show up like this, and the type of anisotropy constitutes a special case of the Stephens model.
Best regards
Andreas Leineweber
Brian H. Toby wrote:
My advice on this question is that one should not use this approach. The Stephens formalism, coded in profile type 4, is better founded by theory. See the GSAS manual and reference to Peter Stephen's J. Appl. Cryst paper from a few years back.
Brian
Christophe Chabanier wrote:
Hello everybody,
i have a question about the GSAS software. Indeed, i would like to know what are exactly the L11, L22, L33....L23 parameters. I saw that these parameters represent the anisotropic microstrain in material. Moreover, there is an empirical expression which uses these parameters as following :
Gamma(L) = L11*h^2 + L22*k^2 + L33*l^2 + 2*L12*hk + 2*L13*hl + 2*L23*kl
I would like to know and understand the physical representation of these parameters and this expression.
Thanks in advance
Christophe Chabanier INRS-�nergie, Mat�riaux et T�l�communications 1650 Blvd. Lionel Boulet C. P. 1020, Varennes Qc, Canada J3X 1S2
_T�l:_ (450) 929 8220 _Fax:_ (450) 929 8102
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