
fitparams = group(amp  = guess(1),
                  de0  = guess(0.1),
                  ss2  = guess(0.002),
                  delr = guess(0.)
                  )

path1 = feffpath('feffcu01.dat')
path1.s02    = param(expr='amp')
path1.e0     = param(expr='de0')
path1.sigma2 = param(expr='ss2')
path1.deltar = param(expr='delr')

out = ff2chi([path1], paramgroup=fitparams)
# print( 'Sum of paths = ', out[:19])
