OpenMM does not give progress for minimization, just wait...
c3c2c3_rosetta_mdr.pdb ...
1 nm
Energy at Minima is -22737.862 kcal/mol
saved  c3c2c3_rosetta_mdr_min.pdb
Cmd: rna_minimize.py -sp c3c2c3_rosetta_mdr.pdb
Execution time: 0:12:49.551  start: 17:03:38 end: 17:16:28  
DONE!