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Alex Granovsky
gran@classic.chem.msu.su

The NREAD is simply the number of passes over a file containing
two-electron integrals which will be performed to complete disk-based
two-electron integral transformation. It is computed based on the
available memory, the overall number of AOs and the number of MOs of
different types (i.e. core, inactive, active, virtual).
Firefly aborts if NREAD is predicted to be too large (i.e. larger than
MXTRFR).

You can reduce NREAD by allocating more memory. Alternatively,
you can increase MXTRFR threshold:

 $xmcqdpt MXTRFR=

However, I strongly suggest you to use semidirect transformation with
XMCQDPT code as described here.

Kind regards,
Alex



On Thu Jul 26 '12 7:10am, Solntsev Pasha wrote
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>Dear Alex.

>I used not latest version but anyway.
>I am working on XMCQDPT job and before i played with different active space and didn't see any problem. Now i have SA-CASSCF(2,3) over first and second states. Total number of states is 3. So with CASSCF - no problem. With XMCQDPT i setup kstate(1)=1,1,1 and wstate(1)=1,1,0 avecoe(1)=1,1,0. Below you will find last part of my output file.

>********** ROUTINE MQSYM  **********************************************
> ###   RESULTS   ###
> # OF SYMMETRY ADAPTED CSFS =         6

> CPU        TIME:   STEP =      0.00 ,  TOTAL =     1335.1 SECONDS (   22.3 MIN)
> WALL CLOCK TIME:   STEP =      0.00 ,  TOTAL =     1338.6 SECONDS (   22.3 MIN)
> CPU UTILIZATION:   STEP =      0.00%,  TOTAL =      99.74%
> ***** CPU TIME FOR MQSYM  =          0.000 SEC.

> ********** ROUTINE MQTRF  **********************************************
> CPU TIME FOR MQHTRN =          0.320 SEC.
> *** ERROR STOP IN SUB.MQTRMC ***
> NREAD IS GREATER THAN MXTRFR.
> NREAD =      1921  MXTRFR =      1000

> ADDRESS 0xF1C2C901 HAS INITIATED PROGRAM ABORT BECAUSE OF FATAL ERROR(S)
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>In my previous jobs NREAD wasn't so high. It was 60. Is this a problem with my input file and we can avoid it by some settings or it is something more serious? I didn't put input/output file(s) but i am ready to provide them.
>
>
>I also have a question not to you but to any familiar with CASSCF person.

>We have polyene chain with phenyl rings from both sides. Problem: construct active space to describe most intense transition (first excited state). From CIS we can see that most intense transition will be 1st state (CIS reference) which consist of:

>           124        131                   0.12189782
>           124        138                  -0.06298572
>           127        130                  -0.13577728
>           127        134                   0.08853389
>           128        131                   0.21288424
>           129        130                   0.93620478

>From TD-DFT(PBE96) also first state
>           127        130                   0.21359097
>           130        127                   0.02713894
>           129        130                   1.00828966
>           130        129                  -0.26609958

>MO#129 is HOMO

>Can we make any deassign about active space? I mean, what would be the best strategy to use NATURAL CIS ORBITALS or consider DFT orbitals that have better agreement with experiment than CIS. I already tried to put all pi orbitals from the chain into active space( 122,123,124,127,128,129) after reordering. In all cases i used 2 virtual orbitals. If we want to get only HOMO->LUMO transition do we need to worry about another transitions, since they also contribute to formation of the 1st excited state. After unsuccessful attempts i decided to check smallest active space and got small problem ( see above).

>Thank you so much for your time and help.

>Pavel.
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