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Alex Granovsky
gran@classic.chem.msu.su

very recently we have published a paper on fluorinated stilbenes

http://pubs.acs.org/doi/pdf/10.1021/jacs.7b09611

where we performed lots of XMCQDPT2/CAS(14,14) computations.

The most efficient and less memory-consuming way to perform such
computations with current Firefly is to use generators-direct code.

I'm attaching a part of a typical input file we used.


As to bigcas option and MQLMB2 memory demands, MQLMB2 allocates
memory using several sequential calls to memory management routines,
not a single call; This explains the behavior you are observing.

Hope this helps.

Kind regards,
Alex Granovsky












On Mon Oct 16 '17 1:03pm, Dawid wrote
-------------------------------------
>Dear Firefly Users,

>I want to perform XMCQDPT2 single-point calculations with
>CAS(14,14), i.e. very large CAS. I encounter numerous issues
>with memory. I have used
>$XMCQDPT2
>bigcas=1
>.
>.
>.
>$END

>to largely reduce memory requirements but it is still not enough.
>Now, I noticed that if I use  either mwords=300 or mwords=320,
>I get following errors:
> ********** ROUTINE MQLMB2 (   1) ***************************************
> ***** ERROR: MEMORY REQUEST EXCEEDS MAXIMUM.
>   301512972 WORDS REQUIRED    300000000 AVAILABLE.

> ADDRESS 0x093F7B87 HAS INITIATED PROGRAM ABORT BECAUSE OF FATAL ERROR(S)
>
>
>OR
>
>
> ********** ROUTINE MQLMB2 (   1) ***************************************
> ***** ERROR: MEMORY REQUEST EXCEEDS MAXIMUM.
>   367923267 WORDS REQUIRED    320000000 AVAILABLE.

> ADDRESS 0x603D7B87 HAS INITIATED PROGRAM ABORT BECAUSE OF FATAL ERROR(S)
>
>
>So why do I have greater requirements when I give more?
>By the way, what can I do to decreases needed memory?
>I provide essential parts of input (I think so):

> $SMP
>  np=4
>  httnp=1
>  smppar=.TRUE.
> $END

> $SYSTEM
>  mwords=300
>  timlim=36000
> $END

> $XMCQDPT
>  bigcas=1
>  inorb=1
>  nstate=15
>  wstate(1)=1,1,1,1
>  edshft=0.02
>  mxbase=30
>  halloc=.TRUE.
>  thrgen=1d-20
>  genzro=1d-20
>  threri=1.0d-20
>  thrcon=1d-8
> $END

>Best wishes,
>Dawid

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