I am trying to involve quantum calculations in my mechanism generation but I can't use mopac. I installed the open source of mopac into my rmg_env but it doesn't work, though it was successfully installed into my rmg_env with conda install -c conda-forge mopac. When I test it with which mopac it doesn't give me the mopac version. However, when I navigate the folders I still see mopac 2016 files in bin under rmg_env. Please, how can I get mopac to work. This the error I get when I run rmg.

Trying MopacMolPM7 attempt 1 of 10 on molecule C=C=CC1C=CC=CC1=C.
Traceback (most recent call last):
File "/home/flames/anaconda3/envs/rmg_env/bin/rmg.py", line 118, in
main()
File "/home/flames/anaconda3/envs/rmg_env/bin/rmg.py", line 112, in main
rmg.execute(**kwargs)
File "/home/flames/anaconda3/envs/rmg_env/lib/python3.7/site-packages/rmgpy/rmg/main.py", line 673, in execute
self.initialize(**kwargs)
File "/home/flames/anaconda3/envs/rmg_env/lib/python3.7/site-packages/rmgpy/rmg/main.py", line 496, in initialize
self.load_database()
File "/home/flames/anaconda3/envs/rmg_env/lib/python3.7/site-packages/rmgpy/rmg/main.py", line 420, in load_database
family.add_rules_from_training(thermo_database=self.database.thermo)
File "/home/flames/anaconda3/envs/rmg_env/lib/python3.7/site-packages/rmgpy/data/kinetics/family.py", line 1269, in add_rules_from_training
reactant.thermo = thermo_database.get_thermo_data(reactant, training_set=True, metal_to_scale_to=metal)
File "/home/flames/anaconda3/envs/rmg_env/lib/python3.7/site-packages/rmgpy/data/thermo.py", line 1343, in get_thermo_data
thermo0 = quantum_mechanics.get_thermo_data(original_molecule) # returns None if it fails
File "/home/flames/anaconda3/envs/rmg_env/lib/python3.7/site-packages/rmgpy/qm/main.py", line 216, in get_thermo_data
thermo0 = qm_molecule_calculator.generate_thermo_data()
File "/home/flames/anaconda3/envs/rmg_env/lib/python3.7/site-packages/rmgpy/qm/molecule.py", line 363, in generate_thermo_data
self.qm_data = self.generate_qm_data()
File "/home/flames/anaconda3/envs/rmg_env/lib/python3.7/site-packages/rmgpy/qm/mopac.py", line 309, in generate_qm_data
success = self.run()
File "/home/flames/anaconda3/envs/rmg_env/lib/python3.7/site-packages/rmgpy/qm/mopac.py", line 129, in run
self.test_ready()
File "/home/flames/anaconda3/envs/rmg_env/lib/python3.7/site-packages/rmgpy/qm/mopac.py", line 112, in test_ready
stderr=PIPE)
File "/home/flames/anaconda3/envs/rmg_env/lib/python3.7/subprocess.py", line 800, in init
restore_signals, start_new_session)
File "/home/flames/anaconda3/envs/rmg_env/lib/python3.7/subprocess.py", line 1551, in _execute_child
raise child_exception_type(errno_num, err_msg, err_filename)
PermissionError: [Errno 13] Permission denied: '/home/flames/anaconda3/envs/rmg_env/bin/mopac'