[solved]why "str_hkl_angle" has "multiplicity" error in my input

iangie

Dear TOPAS users,

I am trying to put an ellipsoid model (idea from Dr. Yu Wang in UNSW, personal communication) in TOPAS input file. but the program always give error message like " Multiplicity for hkl_angle gama -1 is not valid 1"....
May I ask why I can not use "str_hkl_angle" to define a hkl dependent angle?

Thanks.

'------------------try a ellipsoid goethite-----------------------
str
prm long 500 min 300 max 1500
prm short 50 min 10 max 200
prm thick 10 min 5 max 20
str_hkl_angle gama 0 0 1
str_hkl_angle alpha 1 0 0
prm phi =ArcCos(Cos(alpha)/Sin(gama));
lor_fwhm = 0.1 Rad Lam / (Cos(Th) 2 Sqrt((thick Sin(gama) Cos(phi))^2 + (short Sin(gama) Sin(phi))^2 + (long Cos(gama))^2));

......

iangie

This question has already been solved by Alan. Thanks for his below desciption about "str_hkl_angle" keywords. Please forgive my impertinence quoting personal email, but I think this may help other user wants to use this keyword outside of PO macro.

str_hkl_angle returns the angle between the normal to the plane defined and normals of hkls. It is used in for example by the Preferred_Orientation macro.

There is of course a different angle for each multiplicity and hence the multiplicities are iterated over. Thus when using str_hkl_angle two further reserved parameters come into play; these are M and Mi. M is the number of multiplicities for the current plane and Mi the iterator.

The PO macro uses:

str_hkl_angle ang hkl
scale_pks = Sum((c^2 Cos(ang)^2 + Sin(ang)^2 / c) ^ (-1.5), Mi = 0, Mi < M, Mi = Mi+1) / M;

Note that ang is within in the summation and it comprises a different ang for each multiplicity.