DIST(a=2.5,x=2,y=2.5) SHRINK NCI ROTRANGE=10 STEPS=1
CH3Cl.xyz 0a 4y
HCOOH.xyz 1a 4x
HCOOH.xyz 1x 4y

# Trimolecular SN2
# a is O-Cl reacting pair
# x is the intra-acid hydrogen bond
# y is the H-Cl hydrogen bond