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Plane Restraints

It is possibile to apply restraints to an individual atom based on its distance from a plane defined by the normal vector $\vec{n}$ and the atom's reference coordinate (atom properties refx, refy, refz). An atom for which plane restraints are defined experiences restraints only in the direction of $\vec{n}$. Plane restraints are defined as
\begin{displaymath} E_{HARM}= \sum_{{\rm atoms with } h_i<0} \left( -h_i \right... ...} \cdot \left(\vec{r}_i - \vec{r}_i^{ref}\right) \right]^{e} \end{displaymath} (7.2)

where the sum extends over all atoms with negative individual weights $h_i$. The symbols in Eq. 7.2 correspond to those in Eq. 7.1. By default, plane restraints are turned off. To enable plane restraints, a nonzero normal vector $\vec{n}$ has to be specified using the restraints harmonic statement and assigning a negative weight $h_i$ for the atom property HARM. Note that plane restraints are computed only for atoms with $h_i<0$; otherwise point restraints (see Section 7.1.1) are applied, even if a nonzero normal vector is defined. This permits the simultaneous use of point and plane restraints, however, for disjunct sets of atoms. If $\vec{n}=\vec{0}=(0, 0, 0)$, plane restraints are disabled.

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Xplor-NIH 2024-09-13