For POTEntial=3DPO, a restraining function for 3D NOE-NOE
experiments is used.
The intensity of a 3D NOE-NOE crosspeak,
,
between spins **i,j**, and **k**, is
proportional to the product of the individual NOE transfer
efficiencies of each mixing time:

where is the first and the second mixing time,
** R** the cross-relaxation matrix, the
equilibrium magnetization of spins **k**, and **c** a constant.

The 3D NOE-NOE intensity can be approximated by

where and are the distances between spins **i, j** and **j,
k**,
respectively, and the proportionality constant is set equal to one.
The 3D NOE-NOE function is given by

where **S** is the energy constant specified
by the SCALe statement, is the
observed NOE-NOE intensities, and
are error bounds, and **K** is a scale factor specified by
the RSWITch statement. The NOE-NOE connectivity
and the
intensity and error-bound information are provided by
a pair of ASSIgn statements:

The first ASSIgn statement specifies spins **i** and **j**, along
with the observed intensity and the
error bounds and . The second ASSIgn
statement specifies spins **j** and **k**; the three real numbers
following the second selection are irrelevant and can be set
to arbitrary values.
Note: the 3D NOE-NOE function can be used in combination with
R-6 or center averaging. For further details, the reader is referred to
Habazettl et al. (1992a, 1992b) and Bernstein et al. (1992).

Sat Mar 11 09:37:37 PST 1995