Fixed oxDNA topology for circular strands; increased default max_backbone_force

mrdna/segmentmodel.py

@@ -3626,7 +3626,7 @@ E = 0 0 0
             idx = 0
             sidx = 1
             for strand in strands:
-                prev = idx+len(strand.num_nt) if strand.is_circular else -1
+                prev = idx+strand.num_nt-1 if strand.is_circular else -1
                 last = idx if strand.is_circular else -1
 
                 ## Traverse 3'-to-5'
@@ -3666,7 +3666,7 @@ E = 0 0 0
                            delta_translation = 0.22,
                            delta_rotation = 0.22,
                            verlet_skin = 0.5,
-                           max_backbone_force = 5,
+                           max_backbone_force = 100,
                        ):
 
         if seed is None: