Choice of Averaging
Note that all these sums are defined here for restraints created
by a simple NOE ASSIgn statement. See Section 20.2.1 for
an explanation of the treatment of the optional OR clauses.
For AVERage=R6, the
distance between selected sets of atoms is averaged according
to

(20.1) 
where runs
through all possible combinations of distance restraints
between atoms “" in set 1 and atoms “" in set 2.
For AVERage=R3, the
distance between selected sets of atoms is averaged according
to

(20.2) 
where runs
through all possible combinations of distance restraints
between atoms “" in set 1 and atoms “" in set 2.
For AVERage=SUM, the distance between selected sets of
atoms is computed by adding up
single contributions

(20.3) 
where is specified by the MONOmer statement.
The scaling by
is required, in combination with the SUM averaging
option, to scale the distances corresponding to ambiguous
peaks in symmetric multimers.
The difference between the R6 option and the SUM option
is subtle, and is best illustrated with an example:
if two distances are involved in the average, say 3 and 10 Å,
the R6 average will produce an effective distance
of 3.37 Å, and the R6 sum a distance of 2.99 Å, which is
probably the desired result for ambiguous NOESY crosspeaks.
For this reason, the SUM option
should be used rather than the R6 option to treat ambiguities
for observed NOEs.
For AVERage=CENTer,
the distance between selected sets of atoms is
set to the difference between the geometric centers of the atoms,

(20.4) 
Subsections
XplorNIH 20231110