Hi,As some of you may know, i'm working on spin dependent calculations of CrN at the moment. I have a quick and simple question about the spin.f program used to calculate overall SPXAS from two (spin-up and spin-down) xmu.dat files. I'm looking at the nitrogen K-edge.
When i look at my SPXAS plot generated by spin.f, i get something close to experimental data, but with one large peak in the negative intensity region. This doesn't make sense as you cannot have negative energy loss in a XAS plot.
But the spin.f program contains the lines:
elseif (icase.eq.3) then
c factor=0.5 always for SPXAFS
t1 = (y1*ap - z1*am)/2.0/xnorm
t2 = (y2*ap - z2*am)/2.0/xnorm
t3 = (y3*ap - z3*am)/2.0/xnorm
which are obviously subtractions, which will give negative values if, say,
z1>y1.
Does this explain the origin of the 'negative' peak, and if so, i assume
its perfectly reasonable to convert all negative numbers generated to
positive values?
This seems fairly obvious but i wanted to make sure. Let me know if i'm wrong, please.
I've attached a copy of the SPXAS plot i'm talking about. Thanks for any reply, Dave E
Attachment:
N_K-edge.doc
Description: MS-Word document