* $Id: xnd_rdif.html,v 1.1.1.1 2000/00/13 11:10:00 berar Exp $ *>
XND diffusion file and formats.
XND diffusion file and formats.
the default file: xnd_dif.d
In order to avoid a retyping of diffusion tables in the
xnd input file, some tableshave been stored in the xnd_dif.d file
which is by default located in the same directory than the xnd
program.
When a diffusion factor is needed, the program first scans its internal table
read in the input file then tries to find a matching entry in the
xnd_dif.d file. This file contains entry for neutrons and x-ray but the
anomalous scattering factor are not stored inside .Values in the file
comes from the ITC( vol IV. p xx for neutron and p99-100 for analytical x-ray)
The different entries in the file are recognised by the name used in
the variable DifName. For each diffusion name given in the
atomic description of the phase, the program look for an entry which depend
of the experiment.
DifName | Fe | 57Fe | Fe2+ | 57Fe2+
|
---|
neutrons | 0Fe | 57Fe | 0Fe | 57Fe
|
---|
x-ray | Fe | Fe | Fe2+ | Fe2+
|
---|
Neutron entry
They always begin with a digit as the neutron entries allow to distinguish
various isotops. The natural or mean isotop has is referred as 0. The program
uses the values of the diffusion length.
| 1 value
|
---|
DifName | DifCoef
|
---|
0Al | 0.365
|
X-ray scattering: analytical expression
These entries always begin with a letter to be distinguished from neutron entries.
Values in the table comes from
the ITC( vol IV. p99-100)
| 9 values
|
---|
DifName | DifCoef[0] | DifCoef[1] | DifCoef[2] | DifCoef[3] | DifCoef[4] | ...
|
---|
CE | 21.1671 | 2.81219 | 19.7695 | 0.226836 | 11.8513 | ...
|
X-ray scattering: interpolation
These entries always begin with '*' to be recognized, this character is not
stored in the internal table where *fe becomes Fe.
| | | N values taken at
|
---|
DifName | N | ds | ds=0 | s=ds | s=2*ds | s=3*ds | ...
|
---|
| | DifCoef[0] | DifCoef[1] | DifCoef[2] | DifCoef[3] | DifCoef[4] | ....
|
Neutron magnetic entry
These entries always begin with '-' or '_' to be recognized, this character is not
stored in the internal table where -fe becomes Fe.
Analytical expression
These entries always begin with '-'. Values for Jo can be read according
the expansion Aexp(-as2)+...+D according to the ITC(vol C, p391-393)
| 7 values
|
---|
DifName | DifCoef[0] | DifCoef[1] | DifCoef[2] | DifCoef[3] | DifCoef[4] | ...
|
---|
-FE3+ | 0.3972 | 13.244 | 0.6295 | 4.903 | -0.0314 | ...
|
Interpolation
These entries always begin with '_'.
| | | N values taken at
|
---|
DifName | N | ds | ds=0 | s=ds | s=2*ds | s=3*ds | ...
|
---|
| | DifCoef[0] | DifCoef[1] | DifCoef[2] | DifCoef[3] | DifCoef[4] | ....
|
Examples
The following lines are valid entries taken out of the xnd_dif.d file.
0AL 0.345
0AG 0.61
CE 21.1671 2.81219 19.7695 0.226836 11.8513 17.6083 3.33049 127.113 1.86264
CE4+ 20.3235 2.65941 19.8186 0.218850 12.1233 15.7992 0.144583 62.2355 1.59180
Other cases
Specific description have been reserved for some other cases which are not
yet implemented. They use the interpolation format but the DifName does not
begin with a '*', but with another special character depending on the matter.
'&' deals with compton scattering, $ for incoherent neutron scattering ...
JFB June 21th, 1996