Using Molden with MOPAC

Molden works best with mopac93. moapc5.0/6.0 will in general be ok. For ampac and vamp some things will work, while others may not.

To view orbitals and density you have to supply the mopac keyword GRAPH. At the of the mopac run a .gpt file will have been created. This is a binary file, so molden will only be able to read it in on the same platform it was created. (In the molden distribution there is a small program called unmullik which will convert a binary .gpt file to an ascii one. The ascii version can be read by molden on any platform.
There seem to be adapted versions of Mopac93 which write their own ascii .gpt files, these files differ from the ascii files generated by unmullik. One of these if supported when using the molden commandline flag -t.

If you want Molden to display the intermediate geometries of an EF optimisation or TS saddle point, you have to supply the additional mopac keywords:

NOXYZ PRNT=2 COMPFG

If you want Molden to display the intermediate geometries of an IRC calculation add the mopac keywords:

XPRIO LARGE

NOXYZ

Beware of using non-readible characters on the output (such as the date in russian), molden will think it is dealing with a binary format (mopa c .gpt or msf).