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Alex Granovsky
gran@classic.chem.msu.su

normally, XMCQDPT code calls MQCACI two or three times depending
on input options. The use of

 $MCSCF IFORB=.T. $END
 $XMCQDPT IFORB(1)=-1,1,1 $END

allows one to skip the first call only.

The best way to reduce the number of words required by MQCACI
is to decrease the value of MXBASE variable.
It defines the number of subspace vectors used in Davidson
diagonalization. The default is rather large and is printed
in output. Use exetyp=check to find a suitable value to fit
into memory (say ca. 20 or so). You may also need to use CSFs
selection (please drop a post here if you have questions on this).

Note, aug-mcqdpt2 is not the same as xmcqdpt2. As I mentioned in my paper on XMCQDPT:

The systematic overestimation of off-diagonals within MCQDPT2 has been 
documented previously (2005-2006). The development of XMCQDPT was 
completed in 2008, and initially led to development of the so-called 
augmented effective Hamiltonian approach to MCQDPT2 (aug-MCQDPT2, or, 
more precisely, aug-MCQDPT2’) by Bochenkova. This procedure can be 
considered as the attempt to apply a variation of the stabilization 
graph technique to the MCQDPT2’ effective Hamiltonians of sequentially 
enlarged dimensions aimed to minimize effects caused by overestimated 
off-diagonal elements of the effective Hamiltonian.

Kind regards,
Alex Granovsky




On Sun Jan 6 '13 10:41am, Panwang Zhou wrote
--------------------------------------------
>Dear all,

>When performing the XMCQDPT2 calculation I encountered the following problem：
>the job exited at the "ROUTINE MQCACI" and the error information is related to the memory usage:

> ********** ROUTINE MQCACI **********************************************
> ***** ERROR: MEMORY REQUEST EXCEEDS MAXIMUM.
>  1298573444 WORDS REQUIRED    300000000 AVAILABLE.

>Thus, it seems that there are not enough memory to carry this job. However, in my input file I have set

>$MCSCF IFORB=.T. $END
>$XMCQDPT IFORB(1)=-1,1,1 $END

>as described in:
>http://classic.chem.msu.su/cgi-bin/ceilidh.exe/gran/gamess/forum/?C35e9ea902bHW-8295-1009+00.htm

>these settings will 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.

>So, why this error occurred and is there a way to resolve this problem? Thanks.

>The system I studied is the same as ref:
>http://link.springer.com/article/10.1134%2FS1990793108050023?LI=true
>The NACT and NELS I used is also same to the above ref, so this job should be carried out by firefly.

>The part of my input file:
> $CONTRL SCFTYP=MCSCF RUNTYP=ENERGY EXETYP=RUN MAXIT=100 ICHARG=-1
>    MULT=1 FSTINT=.T. GENCON=.T. ITOL=30 ICUT=11 INTTYP=HONDO
>    NOSYM=1 WIDE=.T. MPLEVL=2 $END
> $SYSTEM MWORDS=300 KDIAG=0 NOJAC=100 TIMLIM=60000.0 $END
> $SYSTEM MKLNP=1 NP=12 $END
> $P2P P2P=.T. DLB=.T. $END
> $SMP SMPPAR=.T. $END
> $SCF DIRSCF=.T. FDIFF=.F. NCONV=8 $END
> $TRANS MPTRAN=2 DIRTRF=.T. AOINTS=DIST ALTPAR=.T. MODE=112 $END
> $MCSCF CISTEP=ALDET FULLNR=.F. SOSCF=.T. MAXIT=150 $END
> $MCSCF IFORB=.T. $END
> $DET NCORE=49 NACT=14 NELS=16 NSTATE=6 WSTATE(1)=1,1 $END
> $XMCQDPT NSTATE=2 EDSHFT=0.02 THRGEN=1D-12 $END
> $XMCQDPT IFORB(1)=-1,1,1 WSTATE(1)=1,1,-0 AVECOE(1)=1,1,-0 $END
> $BASIS GBASIS=N31 NGAUSS=6 NDFUNC=1 NPFUNC=1 DIFFSP=.TRUE. $END
> $GUESS GUESS=MOREAD NORB=359 $END
> $MCQFIT $END