$FRAGNAME input group with the second atom of the pair, and
how many such pairs exist.
gives a label (arbitrary), the position of the atom within
the $FRAG1 group, and the 2nd atom's within the $FRAG2.
This line must be repeated times.
Line 4. STOP
the word STOP ends this RDF's pair input.
Lines 2-4 must then be repeated a total of times.
An example will make this all clear. If there is only one
type of fragment used, such as water (so $EFRAG contains
only FRAGNAME=WATER), and assuming that this $WATER group
defining the water EFP has atoms in the order O,H,H:
OO water water 1
dum 1 1
OH water water 4
dum 1 2
dum 1 3
dum 2 1
dum 3 1
HH water water 4
dum 2 2
dum 2 3
dum 3 2
dum 3 3
generated on 7/7/2017