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Re: Discontinuous energy curve from XMCQDPT2 results

Alex Granovsky
gran@classic.chem.msu.su


Dear Panwang Zhou,

I do not think it is discontinuous, it is just not smooth.
It seems it simply consists of two parts and I think
there is nothing wrong with these results.
As far as I understand there are two independent
segments of LIIC path rather than a continuous
interpolation between three geometries. In this
situation I would expect a non-zero angle between
two parts of the path i.e. the path is not a smooth
curve but has a break at CI point. As path is not a
smooth curve, it is natural for energy profiles
to have a break along such a path.

Kind regards,
Alex Granovsky



On Wed May 8 '13 11:50am, Panwang Zhou wrote
--------------------------------------------
>Dear all,

>Recently, I performed a MCSCF(16,14) calculation then following a XMC-QDPT2 calculation on the constructed LIIC curve among the optimized cis-HBDI, CI and trans-HBDI structures, the obtained MCSCF curve is smooth and continuous whereas the obtained XMC-QDPT2 curve is  discontinuous at the CI point (see attachment). I'm not clear why the XMC-QDPT2 curve is discontinuous and how to resolve this problem?

>The following is the part of input file:

> $CONTRL SCFTYP=MCSCF RUNTYP=ENERGY EXETYP=RUN MAXIT=50 ICHARG=-1
>    MULT=1 FSTINT=.T. GENCON=.T. INTTYP=HONDO NOSYM=1
>    ICUT=11 ITOL=30 WIDE=.T. MPLEVL=2 $END
> $SYSTEM MWORDS=480 TIMLIM=60000.0 KDIAG=0 NOJAC=100 $END
> $SYSTEM MKLNP=1 NP=12 $END
> $SMP SMPPAR=.T. HTTNP=1 $END
> $SCF DIRSCF=.T. FDIFF=.F. NCONV=8 $END
> $P2P P2P=.T. DLB=.T. $END
> $TRANS MPTRAN=2 DIRTRF=.T. AOINTS=DIST ALTPAR=.T. MODE=112 $END
> $MCSCF CISTEP=ALDET FULLNR=.F. SOSCF=.T. MAXIT=100 $END
> $MCSCF IFORB=.T. $END
> $DET NCORE=49 NACT=14 NELS=16 NSTATE=6 WSTATE(1)=1,1 DISTCI=12 $END
> $XMCQDPT NSTATE=2 EDSHFT=0.02 THRGEN=1D-12 MXBASE=90 $END
> $XMCQDPT HALLOC=.T. $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

>I have tried to increas the NSTATE in XMCQDPT group, however, the required memory is larger than 480 MWORDS, thus the calculation failed.

>Best Regards!

>Panwang Zhou
>


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