Cut-off for peak profile calculation

oysteinsf

Hi,

I have a problem with the cut-off for peak profile calculations. I am looking at very small features in my data and I get a small step in the calculated profile where the Bragg peak ends. I want to remove this step. My experience is that this is the cut-off in the calculation of the peak profile. In Jana it is possible to adjust this cut-off from the default 8*FWHM to whatever, and it usually solves the issue. I recall doing this in Topas before, but I cant find it again. Is there a way to set this in an .inp file?

Thanks,
Øystein

johnsoevans

TOPAS does this by calculating out to a value where the intensity falls to a specified fraction of that at the peak centre. This allows you to deal with asymmetric peaks properly. It's set by "ymin_on_ymax 0.001" or by the number in brackets in e.g. CuKa2(0.001). Set to a smaller number to calculate out further. This may slow the calculation down for complex structures.