Hi Nic,
The delr and ss values may adopt reasonable values with a negative
amp, but they're almost certainly not the right values. A negative amp
turns the chi(k) upside-down. To make it ft, the other parameters then
have to shift the graph over by half an oscillation, yielding values
of
Dear Nic,
this sounds like your fit is shifted to the experimental chi(k) by half
an oscillation period. Typically, you can recognize this by looking at
the enot value. So what is your enot value like? Does it help changing
the enot starting value by a couple of eV? Finally, (and this is a
On Monday, August 01, 2011 12:36:19 am nicholas@csiro.au wrote:
Just wondering what could I do to make the amp guess value as a positive
number? If I run it and let it float (i.e. guess), the amp becomes
negative in the resulting fits, but the fit has nice delr and ss values
(i.e. make
