peak fitting with other phases. Minimisation not happening well.

rowlesmr

Hi there

I'm having issues in doing peakfitting in the presence of other phases.

I'm looking at an insitu data set, and trying to get a handle on the phases coming and going. Most are unknow, so require peakfitting and indexing (if possible).

My data looks like:

I'm trying to fit peaks like this:

with code like this

	xo_Is
		scale 0.001
		CS_L(@, 81.29313`)
		   xo  4.43 I @  41.15450`
		   xo  6.59 I @  41.27231`
		   xo  7.9  I @  62.97003`
		   xo  8.06 I @  202.21262`
		   xo  8.87 I @  98.57966`
		   xo  9.04 I @  172.75127`
		   xo  9.13 I @  167.21041`

I can't let the peak positions refine freely as they will move a great deal, even though they are very close to their actual positions.

code such as update = Val + 0.1 Change; doesn't seem to damp the effect. Min/max limits don't work, with the peak just sitting at the limit.

I often need to add a peak where there is nothing to kick the minimisation to actually do something, otherwise no parameters actually refine.

Any tips?

mfisch

Try

xo @ 4.43 min = Val - 0.01; max = Val + 0.01; I @ 41.15450`

Probably a CS_L value for each peak with reasonable min/max also helps.

alancoelho

Maybe the 'remove_phase' keyword can be used here. remove_phase is evaluated at the end of a refinement cycle and the phase it is defined in is removed if it evaluates to true.