[molpro-user] multi input processing in version 2010.1

Hans-Joachim Werner werner at theochem.uni-stuttgart.de
Thu Dec 1 10:53:34 GMT 2011

Dear All,
I now implemented a "FORCEINP" option in multi, which forces that all input
is processed also during geometry optimizations and frequency calculations. Normally 
input is skipped during OPTG/FREQ calculations, and the program uses automatically the 
appropriate starting orbitals, occupations etc. Using the FORCEINP option is not recommended
and at your own risk  (just use multi,forceinp;...).

If the program does not converge with neighboring orbitals in optimizations or reaction path
calculations, this is most likely due to root flipping or changes of the character of some
active/inactive orbital along the path. So it is better to look first for the physical reason of the
problem than to fiddle with different starting orbitals.

The stepsize in reaction path calculations can be affected by the STEPMAX option (default is 0.3).
The value if idir (direction) only affects the initial step. I will update the documentation
to clarify this point.

The patch containing FORCEINP is currently being checked on various platforms and should appear 
soon on the server.  

Best regards
Joachim Werner

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