I have set up the VAX QCPE distribution of Mopac 6.0 and a working Unix
conversion(DEC 5000 Ultrix workstation) for anonymous FTP download.
The system is ouchem.chem.oakland.edu. Login as ftp with any password.
The vax distribution tape is in the directory pub/vax. The Unix
conversion is in pub/unix. Some modifications to the makefile and/or
source may be necessary to allow the code to work on other Unix systems.
Also, note that Mopac 6.0 is completely a public domain code.