[RMCProfile-users] Scale factor

Tue Apr 21 12:17:44 BST 2015

Hi Alex,

I wonder if we are running into a difference of terminology here. I know some data reduction software uses the term “F(Q)” for a Q-weighted function, whereas RMCProfile does not (we’d call this “QF(Q)” or something like that).

At the moment the X-ray part of the code can only fit the one function (“our” F(Q)), so one option might be for you to divide your data by Q before inputting into RMCProfile. I suspect that a scale factor might still be necessary, but at least it would be a step forward.

Also from your picture it looks like the program has stopped calculating the F(Q) at ~16.5Å-1, whereas the data continue a bit further; is that intentional? If not, the END_POINT :: keyword might be set to fewer points than the data file actually contains.

Best wishes,
Helen

From: rmcprofile-users [mailto:rmcprofile-users-bounces at rmcprofile.org] On Behalf Of Alejandro Fernandez-Martinez
Sent: 09 April 2015 19:08
To: rmcprofile-users at rmcprofile.org
Subject: Re: [RMCProfile-users] Scale factor

Hi Helen,
Thanks for the feedback.
I think we have understood the problem better now. Actually, the scale factor fitting seems to be working OK. But somehow the F(q)_RMC that is generated by the code in the .out file looks more like a S(q) (indeed, if we multiply it by Q it looks like the F(q)_Exp). So we wonder if the code is actually fitting the F(q). I am pasting here a plot with both functions F(q)_RMC and F(q)_Exp, as reported in the .out file. Any idea about this? Is it maybe just a problem of output?
thanks
[cid:image001.png at 01D075C3.9033A2C0]

Le 09/04/2015 10:14, helen.playford at stfc.ac.uk<mailto:helen.playford at stfc.ac.uk> a écrit :
Hi Alex,

When I’ve tested this the FITTED_SCALE keyword has worked as intended for X-ray data (using the XRAY RECIPROCAL SPACE DATA :: keyword block). There is a quirk in the programming where if you put a double colon after it (like some other keywords have) then this keyword will stop working. If you are using the keyword so it looks like:

> FITTED_SCALE

Then it ought to work. Maybe something else is causing problems? Could you tell us a little bit more about your  simulations? What keyword blocks/data do you have in your .dat file?

Best wishes,
Helen

From: rmcprofile-users [mailto:rmcprofile-users-bounces at rmcprofile.org] On Behalf Of Alejandro Fernandez-Martinez
Sent: 02 April 2015 14:56
To: rmcprofile-users at rmcprofile.org<mailto:rmcprofile-users at rmcprofile.org>
Subject: [RMCProfile-users] Scale factor

Dear list
We are doing RMC simulations of X-ray data. We have included the Fitted_scale keyword.  It looks to us that this is not working. Is there any trick associated with the use of this keyword?
Thanks
Alex

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