Hi Hanyu, Sorry for the confusion. The 'Co.inp' file you attached is actually an Atoms.inp file, not a Feff6 or Feff8 input file. If you run that file through WebAtoms, http://cars9.uchicago.edu/webatoms?url=http://cars9.uchicago.edu/atomsdb/Co.... you'll get a Feff6l input file -- running this with larch> feff6l('feff_Co.inp') will generate `feffNNNN.dat` files that you can use to define Feff Paths, as the examples show... To run Feff8l, you'll have to generate a Feff8 file from WebAtoms (see attached for your Co.inp) To use that to create feffNNNN.dat files, use larch> feff8l('feff8_Co.inp') or, using feffrunner for Feff8 inputs and from python, use: import larch from pylab import loadtxt from larch import Group from larch import Interpreter from larch_plugins.xafs import autobk from larch_plugins.xafs import feffrunner from larch_plugins.xafs import feffdat session = Interpreter() feff = feffrunner.feffrunner('feff8_Co.inp',_larch=session) # run Fef8: feff.run() # OR explicitly run all Feff8 modules in order feff.run(exe='rdinp') feff.run(exe='pot') feff.run(exe='xsph') feff.run(exe='pathfinder') feff.run(exe='genfmt') feff.run(exe='ff2x') # create a Path from a feffNNNN.dat file: testPath = feffdat.FeffPathGroup(filename='feff0001.dat', _larch=session) feffdat._path2chi(testPath,_larch = session) print(testPath) print(dir(testPath)) #### Hope that helps.... --Matt