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Re^3: Speeding up ALTTRF during XMCQDPT2 calculations

Alex Granovsky

Note, no checks on the identical contents of two
WSTATE arrays are performed at present! This means one can specify
the options above for non identical state-averaging as well.
In this case, the results of XMCQDPT2 procedure correspond
to the state-averaging defined by the MCSCF's WSTATE array i.e.
the WSTATE and AVECOE arrays of $XMCQDPT input group are ignored.


On Sun Sep 16 '12 4:49pm, Alex Granovsky wrote
>Dear Thom,

>>Finally, with Firefly v. 8.0.0 it is possible to get rid of the
>>first MQCACI and integral transformation procedures for some types
>>of XMCQDPT2 jobs. These types are, however, the most typically
>>used ones. I'll document this in my next post to this thread.

>Assume the averaging is exactly the same in both SA-CASSCF and
>XMCQDPT2 procedures i.e. the weights defined by the WSTATE arrays
>are the exactly the same and refer to the same states. Provided
>this is indeed the case, one can avoid the first integral transformation
>and CASCI procedure (performed by the routine MQCACI) by overlapping
>part of calculations with those performed at the MCSCF stage and
>reusing them at XMCQDPT2 stage.

>To use this feature, one needs to direct MCSCF code to form
>semi-canonical Fock orbitals and to save core and active Fock
>operators. This can be done as follows:


 $mcscf iforb=.t. $end

>One also needs to instruct QDPT code to reuse this information:


 $xmcqdpt iforb(1)=-1,1,1 $end

>This will do the trick.  

>Kind regards,


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