Selecting terminal links exclusively

[fgrunewald]

Is there a way to apply a link only to the terminals of a polymer via the .ff file for the following scenario:

case
1: A-B-B-B-B-A  -> link is not applied  
2: B-B-B-B-B-B  -> link is applied but only to the termini

Using the current ff format I can define non-edges like so:

[ link ]
resname "B"
[ atoms ] 
B { }
+B { }
[  non-edges ]
B +B

The link is correctly applied to the termini in case 2, but is also applied to the second to last B in case 1. Is there anything I'm missing in the syntax that could provide this. @pckroon

[pckroon]

[ link ]
resname "B"
[ atoms ] 
B { }
+B { }
[  non-edges ]
B +B
B +A

maybe? There's a reason why we started using Modifications for termini, rather than the non-edges links though...