OpenMM does not give progress for minimization, just wait...
ariafit_1_slc.pdb ...
Traceback (most recent call last):
  File "/home/ubuntu/rna-tools/rna_tools/tools/md/rna_minimize.py", line 42, in <module>
    pdb = PDBFile(f)
  File "/home/ubuntu/miniconda3/lib/python3.8/site-packages/openmm/app/pdbfile.py", line 95, in __init__
    pdb = PdbStructure(inputfile, load_all_models=True, extraParticleIdentifier=extraParticleIdentifier)
  File "/home/ubuntu/miniconda3/lib/python3.8/site-packages/openmm/app/internal/pdbstructure.py", line 152, in __init__
    self._load(input_stream)
  File "/home/ubuntu/miniconda3/lib/python3.8/site-packages/openmm/app/internal/pdbstructure.py", line 164, in _load
    self._add_atom(Atom(pdb_line, self, self.extraParticleIdentifier))
  File "/home/ubuntu/miniconda3/lib/python3.8/site-packages/openmm/app/internal/pdbstructure.py", line 782, in __init__
    y = float(pdb_line[38:46])
ValueError: could not convert string to float: ' 4.801 -'
DONE!