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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

>

Thu May 9 '13 3:06am

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