Alan,
I do not want to take the decision out of the author, but the
contrary. When programs just only plot in one scale, than the author
is forced to use that one. Can I plot in square root or in Q space
with Topas if I like to do that?
cheers,
Luca
On Feb 21, 2007, at 10:28 PM, AlanCoelho wrote:
I was not aware of Journals having rules stating that data must be
plotted
in square root scale and this is precisely the point. I certainly
do not
want an edict stating that authors must do so. It should be up to
the author
to choose whatever x-axis and y-axis scales that best shows up
features.
If an author is writing a paper on an instrumet correction, say for
example
cylindrical or PSD correction, then it is sensible to use 2Th.
Thus please do not take these decisions away from the author.
And I was referring to the Fourier transform of the whole pattern
as is done
in PDF work not on a peak by peak basis for correcting aberrations. I
brought up the point because when people talk about Q space
especially for
comparison purposes there's typcally a conversion to Q space. A
quick visual
display opearting on a point by point basis is adequate in most
cases but
for analysis the conversion should be done properly; a point missed
by many.
cheers
alan
-----Original Message-----
From: Luca Lutterotti [mailto:[EMAIL PROTECTED]
Sent: Thursday, 22 February 2007 6:59 AM
To: rietveld_l@ill.fr
Subject: Re: Powder Diffraction In Q-Space
Alan,
if it is trivial to plot in the square root I presume it is already
available in Topas as well GSAS and Fullprof just to mention few. And
if it is so trivial and already available as a button options why no
one is using it. Why every time I look at a paper with a Rietveld
refinement I can only appreciate the big peaks and why the residuals
are so little meaningful at end? Every one can choose what he prefers
obviously, but why all (without exceptions) are using not exactly the
best way to just do a plot? Should not be trivial?
Conversion from 2theta - d -1/d is trivial in MY OPINION. This is
really a problem of the programmer not of the users (in a Rietveld
list). Constant step or variable step? Why it should influence the
conversion except for the speed of the conversion. I am using fast
fourier transform in my program for computing peak profiles directly
from distribution of crystallites and microstrain; I don't assume any
constant step, but seems like I can do it.
And this step or FT has really nothing to do with the original post
of Klaus-Dieter who was focusing on just asking people if we can try
to get used to a common way to plot data different from the
conventional one. There are obviously favorable points and cons. Why
we cannot discuss it. Seems like for the Rietveld users is not so
trivial.
Oh, and no one is setting up web sites just to show
opinions.........may be these were already there.......
Cheers,
Luca
On Feb 21, 2007, at 8:11 PM, AlanCoelho wrote:
Whether a program has a button to display data as a function of 1/d
or a
button to take the square toor of intensities is trivial to the
point of not
being talked about much less setting up web sites to get opinions.
The only point worth talking about is how a conversion from 2Th to
1/d is
done in regards to takeing the fourier transform of a powder pattern.
alan
-----Original Message-----
From: Joerg Bergmann [mailto:[EMAIL PROTECTED]
Sent: Thursday, 22 February 2007 4:30 AM
To: rietveld_l@ill.fr
Subject: Re: Powder Diffraction In Q-Space
It's a principle of software design not to presume any kind of
equidistant data. Unfortunately, file formats for non-equidistant
data are seldom. So I could not implement any in BGMN, until now.
But, in principle, there is no restriction.
Regards
Joerg Bergmann
