[molpro-user] Molpro vs Qchem MP2 single point energy calculation of ethylene differences

[Alan Chien]

Ah, I see. Very helpful!

Thanks a bunch!

~Alan Chien


On Wed, Jan 22, 2014 at 4:14 AM, Grant Hill <Grant.Hill at glasgow.ac.uk>wrote:

> Dear Alan,
>
> I’ve no experience with the Qchem program, but I’m guessing that it does
> not use the frozen core approximation by default. If I change your MP2
> directive to {mp2;core,0} I get:
>
> !MP2 total energy                    -78.429489771679
>
> Best regards,
>
> Grant
>
>
>
> On 21 Jan 2014, at 20:35, Alan Chien <alandc at umich.edu> wrote:
>
> > Hello all. I'm a new user of Molpro and was running a few little tests
> on my newly installed 2012.1.9 version of Molpro :D. However, I'm getting
> some weird results.
> >
> > So, I'm comparing an MP2 single point energy calculation of ethylene
> between Molpro and Qchem.
> >
> > I get the same HF energy, but differing MP2 energies at the same
> geometry.
> >
> > Molpro: HF= -78.06321916, MP2= -78.39895488
> > Qchem: HF= -78.0632189754, MP2= -78.4294907701
> >
> > I looked over my inputs (provided below) and they seem fine…any
> suggestions?
> >
> > I'll provide outputs if people want them.
> >
> >
> > QCHEM IMPUT
> > -----------------------------------------------------------
> > $molecule
> > 0 1
> > C       -2.0293377388      1.5831581629      0.0000000000
> > C       -0.6979276316      1.6261615210     -0.0000000000
> > H       -2.5974389181      2.2373976708      0.6547741027
> > H       -2.5540361699      0.8936222030     -0.6547741027
> > H       -0.1732292005      2.3156974809      0.6547741027
> > H       -0.1298264523      0.9719220131     -0.6547741027
> > $end
> >
> > $rem
> > Exchange HF
> > Correlation MP2
> >
> > basis cc-pvtz
> >
> > symmetry false
> > sym_ignore true
> > unrestricted false
> >
> > jobtype sp
> > $end
> > -----------------------------------------------------------
> >
> >
> >
> > MOLPRO INPUT
> > -----------------------------------------------------------
> > ***, Ethylene Geom Opt
> > symmetry=nosym
> > geometry={
> > C       -2.0293377388      1.5831581629      0.0000000000
> > C       -0.6979276316      1.6261615210     -0.0000000000
> > H       -2.5974389181      2.2373976708      0.6547741027
> > H       -2.5540361699      0.8936222030     -0.6547741027
> > H       -0.1732292005      2.3156974809      0.6547741027
> > H       -0.1298264523      0.9719220131     -0.6547741027
> > }
> > basis=VTZ
> > hf
> > mp2
> > -----------------------------------------------------------
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> > Molpro-user at molpro.net
> > http://www.molpro.net/mailman/listinfo/molpro-user
>
>
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