Where is MOPAC?
If you have installed a version of our software that installs MOPAC, then you would access MOPAC from within Chem3D. If you launch Chem3D, you should see a MOPAC menu. If you do not see a MOPAC menu, then either your version of Chem3D does not come with MOPAC or you have moved the Chem3D application from the original location. The Chem3D application must be at the same level as the CSMopac folder. If you want to move the Chem3D application (to your desktop for example), you must make a shortcut (alias for Mac users) of the application and move the shortcut to your desktop.