More recent versions (MOPAC2007, MOPAC2009, MOPAC2012, MOPAC2016) are not open-source. There is plenty of other sites which distribute some flavour of MOPAC - CCL archives, funet archives, SourceForge, GitHub etc.

http://www.ccl.net/cca/software/MS-DOS/mopac_for_dos/index.shtml http://www.nic.funet.fi/pub/sci/chem/qcpe/mopac6.0/ https://sourceforge.net/projects/mopac7/ https://github.com/metapfhor/MOPAC

Reference: Stewart, James J.P., Journal of computer-aided molecular design 4(1) (1990) 1-103.

Description & Use:

MOPAC is one of the most favourite and well-known semiempirical packages which enables MNDO, MINDO/3, AM1 and PM3 calculations.

Quick start: check the included manuals

Program status:

The current package contains MOPAC 7 binaries of primary version compiled for the particular Android hardware platforms and adapted for running in generic, stock devices. The app requires permission to access the file-storage. It works completely offline and does not contain ads.

License:

The distribution is published for free at Mobile Chemistry Portal and Google Play Store with kind permission of James Stewart. We are also grateful to metapfhor (GitHub, https://github.com/metapfhor/MOPAC) for ready-to-compilation form of MOPAC 7 source code.

For more details on licenses of used software, please check the included README file and the corresponding license files inside of the package.

Contact:

Compilation of the source code for Android/Windows as well as the Android/Windows app development was done by Alan Liška (alan.liska@jh-inst.cas.cz) and Veronika Růžičková (sucha.ver@gmail.com), J. Heyrovský Institute of Physical Chemistry of the CAS, v.v.i., Dolejškova 3/2155, 182 23 Praha 8, Czech Republic.

Website: http://www.jh-inst.cas.cz/~liska/MobileChemistry.htm