$LIBE group  (required if linear bends are used in $ZMAT)
 
A degenerate linear bend occurs in two orthogonal planes,
which are specified with the help of a point A.  The first
bend occurs in a plane containing the atoms I,J,K and the
user input point A.  The second bend is in the plane
perpendicular to this, and containing I,J,K.  One such
point must be given for each pair of bends used.
 
APTS(1)= x1,y1,z1,x2,y2,z2,...  for linear bends 1,2,...
 
Note that each linear bend serves as two coordinates, so
that if you enter 2 linear bends (HCCH, for example), the
correct value of NZVAR is M-2, where M=3N-6 or 3N-5, as
appropriate.