# Re: [Ifeffit] synthesis of EXAFS via larch

Hi Katy,


On Tue, Mar 20, 2018 at 11:34 AM, Katy Smith <katy.g.sm...@gmail.com> wrote:

> I seem to be able to make some progress in using Larch, thanks to the
> developers. I wish to produce a plot in R rather than k, what would be the
> equivalent commands to ff2chi, path.k etc as per the
> /examples/feffit/doc_feffdat3.lar?
>

The sum with ff2chi only sums in k-space.  But the output is ready to do
a Fourier transform with xftf (short for "XAFS Fourier Transform
Forward").  So, building on doc_feffdat3.lar,  you could do

# sum of paths (assumed to be defined already), writing chi(k) to
"mysum":
ff2chi([path1, path2, path3, path4, path5], group=mysum)

# now do an XAFS Fourier transform on that group to go from k to R space:
xftf(mysum,   kweight=2,  kmin=3, kmax=15, window='kaiser', dk=4)

# plot of |chir(R)| for this sum
plot(mysum.r,  mysum.chir_mag, label='sum of paths', xlabel=r'$R \rm\,(\AA)$',ylabel=r'$|\chi(R)| \rm\,(\AA^{-3})$')

We're working to release the next version of Larch very soon, which
includes common xafs plotting commands so that the
last line there could be written as "plot_chir(mysum, label='sum of
paths')".

--Matt

_______________________________________________
Ifeffit mailing list
Ifeffit@millenia.cars.aps.anl.gov
http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit