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Alex Granovsky
gran@classic.chem.msu.su

for RHF/ROHF/UHF, the only vailable shift option is $SCF SHIFT=.T. $END
However, this does not work with SOSCF or DIIS turned on and the value
of shift is selected dynamically with current versions of Firefly.  

On the other hand, for RDFT/RODFT/UDFT, there is another available option,
namely $SCF FSHIFT=value $END. It is set to FSHIFT=0.1 by default,
and is in effect only for DIIS and only if $SCF SHIFT=.T. $END
is set as well. The FSHIFT indeed represents the value of the fixed,
constant shift of virtuals that is used by the DFT code.
 
Hope this helps.

Regards,
Alex Granovsky


On Sat Dec 19 '09 12:31pm, Patrick SK Pang wrote
------------------------------------------------
>Dear all,

>Can "$SCF SHIFT=.T. $END" make the virtual orbital energies shift to solve the SCF convergence problem? If yes, how can I set the shift value? I do the PCM job using 6-31++(d,p). I want to try different values to solve the SCF convergence problem.

>Thanks!

>Patrick