MOPAC is now "Open Access," it does not use a license.
Do not request a license.
Downloads: For current version number click here
Download 64-bit MOPAC2016 for Windows (includes a small run-time window)
Instructions for use with Chem3D.
Download 64-bit MOPAC2016 for LINUX Tested on Ubuntu and Red Hat
For other flavors of Linux: The version of glibc that the Linux OS uses must be identified. If the attempt to install MOPAC works, great! If it complains that glibc is missing, identify which version of glibc is used by the Linux operating system, then use the appropriate CentOS version. These are: CentOS 5: glibc-2.5 CentOS 6: glibc-2.12, CentOS 7: glibc-2.17.
The following versions of MOPAC are no longer supported.
They can be downloaded, but might be out-of-date and not run.