LocalCoordinatesSite¶

class
OpenMM::
LocalCoordinatesSite
¶ This is a
VirtualSite
that uses the locations of three other particles to compute a local coordinate system, then places the virtual site at a fixed location in that coordinate system. The origin of the coordinate system and the directions of its x and y axes are each specified as a weighted sum of the locations of the three particles:origin = w_{1} r_{1} + w_{2} r_{2} + w_{3} r_{3} None
xdir = w_{1} r_{1} + w_{2} r_{2} + w_{3} r_{3} None
ydir = w_{1} r_{1} + w_{2} r_{2} + w_{3} r_{3} None
For the origin, the three weights must add to one. For example if (w_{1} , w_{2} , w_{3} ) = (1.0, 0.0, 0.0), the origin of the local coordinate system is at the location of particle 1. For xdir and ydir, the weights must add to zero. For excample, if (w_{1} , w_{2} , w_{3} ) = (1.0, 0.5, 0.5), the x axis points from particle 1 toward the midpoint between particles 2 and 3.
The z direction is computed as zdir = xdir x ydir. To ensure the axes are all orthogonal, ydir is then recomputed as ydir = zdir x xdir. All three axis vectors are then normalized, and the virtual site location is set to
origin + x*xdir + y*ydir + z*zdir
Methods
LocalCoordinatesSite()
Create a new LocalCoordinatesSite()
virtual site.getOriginWeights()
Get the weight factors for the three particles when computing the origin location. getXWeights()
Get the weight factors for the three particles when computing xdir. getYWeights()
Get the weight factors for the three particles when computing ydir. getLocalPosition()
Get the position of the virtual site in the local coordinate system. 
LocalCoordinatesSite
(int particle1, int particle2, int particle3, const Vec3 &originWeights, const Vec3 &xWeights, const Vec3 &yWeights, const Vec3 &localPosition)¶ Create a new
LocalCoordinatesSite()
virtual site.Parameters:  particle1 – the index of the first particle
 particle2 – the index of the second particle
 particle3 – the index of the third particle
 originWeights – the weight factors for the three particles when computing the origin location
 xWeights – the weight factors for the three particles when computing xdir
 yWeights – the weight factors for the three particles when computing ydir
 localPosition – the position of the virtual site in the local coordinate system

const Vec3 &
getOriginWeights
() const¶ Get the weight factors for the three particles when computing the origin location.

const Vec3 &
getXWeights
() const¶ Get the weight factors for the three particles when computing xdir.
