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Veinardi Suendo
vsuendo@chem.itb.ac.id

We had tried your suggestion, it seems the program works better, but we still faced difficulties when working with quite large molecules. Is there any way to divide the required memory? Especially, they need quite a lot for SAAP. Thank you in advance,

Best regards,

Veinardi

On Thu May 21 '09 8:50pm, Alex Granovsky wrote
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>Hi,

>1. The memory allocated using MWORDS/MEMORY keywords is allocated
>on a per process instance basis. You are trying to allocate
>approximately 4*3GB = 12 GB RAM but only have 8 GB of RAM available.
>This causes excessive paging and seriously degrades performance,
>as well as the lifetime of our HDDs.

>Try to run your job requesting only e.g. 260 MWORDS or perhaps
>even smaller amount.

>Actually, there are already multiple threads on this forum discussing
>optimal memory allocation strategies running in parallel on SMP/multi-core systems.

>2. Note that the following p2p settings are only relevant for MP2 at present:

>

 $P2P xdlb=.t. mxbuf=2048 $END

>Moreover, mxbuf=2048 (p2p buffer size in kilobytes) is only
>recommended for shared memory version of p2p interface, which is
>available only for Windows and OS X at present. Otherwise, the
>default, much smaller size is optimal. Actually, you are setting p2p
>buffer to be 2 MB per each process; however, it is allocated
>(and thus consumes some extra memory) but is never used.

>Regards,
>Alex
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>On Wed May 20 '09 10:04am, Veinardi Suendo wrote
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>>Dear Prof. Alex and Firefly users,

>>Recently, we are working on CI calculation to obtain UV absorption spectra of porphyrin related molecules using Firefly. However, we faced some problems when we deal with a slightly higher basis set or using TDDFT calculation. The calculation seems to work properly, but I found that the memory becomes an important issue. Here, we observed that the processors were idle in a quite long period while the program took almost all memory. In this calculation, we carried out on a single PC with Intel Core2 Quad Processor Q9400, CentOS 5.3 64 bit with RAM of 8GB. In the beginning everything was fine, the program use all cores up to 100 % (4x100%), however, when they start the CI calculation, I do not know why, it seems they really need a lot of memory so they took all 8GB of RAM + 8 GB of swap memory. Is there any option to divide the jobs efficiently, so there will not much processors idle? Below, I list as well the header of our input file:

>> $CONTRL SCFTYP=RHF CITYP=TDDFT INTTYP=HONDO
>>  EXETYP=RUN MAXIT=100 MULT=1 LOCAL=NONE ICUT=11
>>  DFTTYP=B3LYP ITOL=30 D5=1 ICHARG=0 $END
>> $SYSTEM TIMLIM=31536000 MEMORY=400000000 KDIAG=0 FASTF=.TRUE. $END
>> $P2P p2p=.t. dlb=.t. xdlb=.t. mxbuf=2048 $END
>> $SMP Call64=.t. $END
>> $BASIS GBASIS=N31 NGAUSS=6 NDFUNC=1 NPFUNC=1 $END
>> $D5 D5=.TRUE. F7=.TRUE. G9=.TRUE. $END
>> $GUESS GUESS=MOREAD NORB=302 KDIAG=0 PRTMO=.TRUE. $END
>> $INTGRL SCHWRZ=.TRUE. NOPK=1 PACKAO=.TRUE. $END
>> $TDDFT NSTATE=60 ISTATE=1 TDA=.FALSE. $END
>> $SCF DIRSCF=.TRUE. FDIFF=.FALSE. NCONV=6
>>  EXTRAP=.TRUE. DAMP=.TRUE. SHIFT=.TRUE. RSTRCT=.TRUE.
>>  DIIS=.TRUE. SOSCF=.FALSE. $END
>> $STATPT OPTTOL=0.0001 NSTEP=400 Method=GDIIS HESS=GUESS $END
>> $DATA

>>I am looking forward to hear from you.

>>Best regards,

>>Veinardi