Revision 1 as of 2006-04-06 19:39:49

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I General Questions

II Global Optimization

III Crystal Modelization

Diffraction data

General questions

Anchor(gen1) My question is not answered here !

Anchor(gen2) How can I get news about the evolution (new releases etc..) of Fox ?

Anchor(gen3) What is an "Object" ?

II Global Optimization

Anchor(glob1) I know 'Simulated Annealing' (SA), why do you recommend to use "Parallel Tempering" (PT) ?

Anchor(glob2) My optimization has reached [enter cost here]. Has it converged enough ?

Anchor(glob3) Fox does not optimize profile/unit cell parameters, even if I check the parameters to be optimized ! Why ?

Anchor(glob4) What parameters can/should I optimize ?

Anchor(glob5) What objects should I add in the Optimization object ?

Anchor(glob6) How can I remove an object from an Optimization ?

III Crystal Modelization

Anchor(cryst1) How can I take into account Special Positions ? What is the Dynamical Occupancy Correction ?

Anchor(cryst2) What happens when two atoms are completely overlapping ? Does one disappear ?

Anchor(cryst3) How can I ensure that the algorithm keeps the correct formula for my compound ?

Anchor(cryst4) How can I use an Antibump criterion ? How can I see the Antibump parameters ? Does it prevent the "merging" of atoms using the Dynamical Occupancy Correction ?

Anchor(cryst5) Should I restrict the positionnal parameters (fractionnal coordinates) to (0;1) using the parameter's limits ? Same for angles in (0,2pi)?

IV Diffraction data

Anchor(diff1) I copied the powder pattern 2theta zero (shift) from my profile fitting program, but it looks wrong ?

Anchor(diff2) How can I change the powder pattern background points ?

Anchor(diff3) Is it possible to exclude parts of a powder pattern ? Can I remove an exclude region ?

NOTE: the powder patterns in these regions are still computed, so if you want to avoid computing the higher parts of the powder pattern, rather use the "Max sin(theta)/lambda" entry field.

Anchor(diff4) Can I use several data sets to refine a single crystal structure ?

Anchor(diff5) You recommend to use only low-angle data, but why discard this information ? High-angle reflections are important for structure determination !

Anchor(diff6) What shall I put in the "linear polarization rate" field ?

Anchor(diff7) Do you take into account the magnetic scattering of neutrons ?

Anchor(diff8) The Rwp and graphs look fine, but the optimized preferred orientation parameters are wrong !