Trace: • n

# n

**[ neutron_data]**

Signals the use of neutron atomic scattering lengths.Scattering lengths for isotopes can be used by placing the isotope name after “*occ*” as in:

occ 6Li 1

occ 36Ar 1

The scattering lengths data, contained in the file NEUTSCAT.CPP, is from

www.ccp14.ac.uk/ccp/web-mirrors/neutrons/n-scatter/n-lengths/LIST~1.HTM

Constant wavelength neutron diffraction requires a Lorentz correction using the Lorentz_Factor macro (defined in TOPAS.INC); it is defined as follows:

scale_pks = 1 / (Sin(Th)^2 Cos(Th));

**[ no_LIMIT_warnings]**

Surpresses LIMIT_MIN and LIMIT_MAX warning messages.

**[ normalize_FCs]**

If defined then site fractional coordinates are normalized. Normalization of a particular fractional coordinate does not occur if it has *min**/max* limits, is part of a *rigid* body or part of a site constraint of any kind.

**[ numerical_area E]**

Returns the numerically calculated area under the phase.