Normally, no weighting is applied during the fitting i.e. all atoms
are weighted equally. The WEIGHT command causes the fitting to
be weighted by the mean of the B-values in the equivalent
atoms. Normally, you wouldn't use this with real B-values, but with
some other weight parameter (e.g. SSAP scores).
The BWEIGHT command weights the fitting by the inverse of the
mean of the B-values in the equivalent atoms. This is useful for
genuine weighting by B-values (i.e. the mobile set atoms will be less
heavily weighted).
The NOWEIGHT command switches off weighting.
Atoms can also be removed from consideration in the fitting and RMS
deviation calculations using temperature factors as a cutoff. The
BVALUE command allows you to specify a B-value cutoff and any
atoms with B-values greater than this value will be ignored
completely in both the fitting and RMS deviation calculations. The
B-value may not be higher than this value in either the reference set
or the mobile set. For example, if you specify 10, then atoms with
B-values greater than 10 will be ignored.
By specifying a negative value for BVALUE, you require that any
atoms with B-values less than the absolute value you specify will be
ignored. For example, if you specify -10, then atoms with B-values
less than 10 will be ignored.
The value may be followed by an optional REF or MOB
parameter which restricts checking of B-values to the specified
structure.