Calculating NMR observables with mdtraj.nmr()

An error occurred while executing the following cell: ------------------ shifts = md.nmr.chemical_shifts_spartaplus(trj) shifts[0:10] ------------------  OSErrorTraceback (most recent call last)  in  ----> 1 shifts = md.nmr.chemical_shifts_spartaplus(trj)  2 shifts[0:10] /nix/store/rg3m2aq0i0897r4cmx3a3cy1gjx0ragp-python3.8-mdtraj-0.0/lib/python3.8/site-packages/mdtraj/nmr/shift_wrappers.py in chemical_shifts_spartaplus(trj, rename_HN)  275 binary = find_executable(SPARTA_PLUS)  276 if binary is None: --> 277 raise OSError('External command not found. Looked for %s in PATH. `chemical_shifts_spartaplus` requires the external program SPARTA+, available at http://spin.niddk.nih.gov/bax/software/SPARTA+/' % ', '.join(SPARTA_PLUS))  278   279 names = ["resSeq", "resName", "name", "SS_SHIFT", "SHIFT", "RC_SHIFT", "HM_SHIFT", "EF_SHIFT", "SIGMA"] OSError: External command not found. Looked for sparta+, SPARTA+, SPARTA+.linux in PATH. `chemical_shifts_spartaplus` requires the external program SPARTA+, available at http://spin.niddk.nih.gov/bax/software/SPARTA+/ OSError: External command not found. Looked for sparta+, SPARTA+, SPARTA+.linux in PATH. `chemical_shifts_spartaplus` requires the external program SPARTA+, available at http://spin.niddk.nih.gov/bax/software/SPARTA+/

(nmr.ipynb; nmr_eval.ipynb; nmr.py)