cabb99 / open3spn2

An implementation of the 3SPN2 and 3SPN2.C coarse-grained DNA forcefields in OpenMM
MIT License
18 stars 8 forks source link

Topology issue when loading circular DNA (plasmids) #5

Open Heezch opened 4 years ago

Heezch commented 4 years ago

Dear Carlos,

First of all, what a nice project! I want to simulate plasmids (dsDNA with circular topology). However, the bonds connecting start-to-end do not seem to be connected during the simulation.

All steps followed from the example starting from PDB (and removing the protein part) work fine. Even the simulation seems to run with constant energy and temperature. Only after visual inspection of the trajectory I noticed the circular DNA object breaks.

I think it has to do how the pdb file deals with standard residue bonds only. But I haven't found a way to by-pass or introduce this exception of circular topology.

Do you have any suggestions to make the code work with circular topology as well? Of course I am happy to help!

Starting pdb and coarse grained pdb (generated with openMM) containing a plasmid of 500 bp coarse_grained_plasmid_500.txt atomistic_plasmid_500.txt