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Re^6: Speeding up ALTTRF during XMCQDPT2 calculations

Alex Granovsky

Dear Thom,

the last hint is to use mwords to allocate memory for all Firefly
processes except grand master (and except local master processes
running in XP mode) and using $system masmem keyword to allocate
memory for master processes. This can be useful as XMCQDPT2
summation requires more memory than MCSCF and ALTTRF stages.

If masmem is not given, masters will allocate amounts defined by the
$system mwords or $system memory keywords. If it is given, then they
will allocate the maximum of masmem, mwords, or memory.

mamsem is interpreted as millions of words if its value is less
than 534. Alternatively, it is interpreted as words rather than
millions of words.

Kind regards,

On Tue Sep 18 '12 11:09am, Thomas wrote
>Dear Alex,

>Thank you for your suggestions, I've managed to speed up my calculations quite a bit.
>Kind regards,
>On Sun Sep 16 '12 9:57pm, Alex Granovsky wrote
>>Dear Thom,

>>On Sun Sep 16 '12 7:57pm, Thomas wrote
>>>Dear Alex,

>>>Thank you for this information. I'll try if parallel execution will improve performance.

>>>I have one question regarding skipping the MQCACI step. Normally, I run the MCSCF part in parallel with

to punch orbitals with extra accuracy, and then do the XMCQDPT2 part separately in multithreading mode with
to read in the converged orbitals and skip the MCSCF step. Am I correct in assuming that in this scenario it is not possible to skip the MQCACI step?
>>>Kind regards,

>>It is still possible to avoid first MQCACI this way, although the way I described before is a bit more economical.

>>To avoid first MQCACI procedure, add the following to the input
>>file for the MCSCF stage:


 $contrl wide=.t. $end
! The sd=.t. option should be used to preserve the exact symmetry
! of MCSCF orbitals during various transformations e.g. generation 
! of natural orbitals or Fock orbitals
 $mcscf iforb=.t. sd=.t. $end

>>Upon completion, extract all OPTIMIZED MOs and then moread all of them, including virtual ones in the input for the subsequent XMCQDPT stage.
>>In addition, add the following to the XMCQDPT input:


 $xmcqdpt inorb=2 iforb=0 $end

>>Kind regards,

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