[molpro-user] problem regarding eom-ccsd

[Tatiana Korona]

Hi!

There are several problems with your input:

1) Using multi before ccsd and eom is a) unnecessary, b) can lead to 
unpredicable results, if orbitals put into ccsd and then eom-ccsd are not 
SCF orbitals (i.e. using other orbitals than the canonical SCF orbitals is 
not strictly forbidden, as long as occupied and virtual spaces are 
orthogonal to each other and orbitals are orthogonal wmong themselves, but 
you should know what you are doing).

2) In molpro only EOM-CCSD (NOT EOM-CCSD(T)) exists. Of course one can
calculate CCSD(T) for the ground state, but with EOM only CCSD should be
used. Summarizing, the combination
{ccsd
eom....}

should be used

3) Giving 1.1 (ground state) is unnecessary in eom.

4) put,molden in your input will save the SCF orbitals only. For EOM one 
can calculate and save 1-electron excited densities, but this means 
calculating properties too (2 times more expensive), see 
$molpro/example/hf_eom_prop.com. Then e.g. the population analysis can be 
made.

Best wishes,

Tatiana


On Mon, 8 Dec 2008, Rajagopala Reddy seelam wrote:

> hai,
>
> Dear Molpro-User:
>
> I want to calculate the excitation energy of the first two excited singlet
> states of para-difluorobenzene molecule. The point group of this molecule
> is D2h. And the corresponding excited state symmetry is 1B2u (S0) and 1B1u
> (S1), respectively. When i ran the job it is calculating the excitation
> energy of the first state but for the second state it failed with the
> following error message.
>
> "  EOM-CCSD FOR  1 EXCITED STATES OF SYMMETRY 5    STATES:     1
>
>
> Iter. Vector     |HC-EC|         E_new-E_old   Excitation energy    Total
> energy
>
>
> Record   6064.8 too small: 1307484 1315332
> ? Error
> ? Record too small (kcp)
> ? The problem occurs in cckext
>
> ERROR EXIT
> CURRENT STACK:      MAIN "
>
> The following is the input, i have used for this Job.
>
>
> ***,p-c6h4f2 eom-ccsdt calculation
> print,orbital;
> memory,300,m
> basis{f=aug-cc-pvdz,c=aug-cc-pvdz,h=cc-pvdz}
> geomtyp=xyz;
> geometry={12
> para-difluorobenzene eom-ccsd(t) calculation (single point calculation)
> c   0.000000    0.000000    1.374968
> c   0.000000    1.227353    0.703641
> c   0.000000    1.227353   -0.703641
> c   0.000000    0.000000   -1.374968
> c   0.000000   -1.227353   -0.703641
> c   0.000000   -1.227353    0.703641
> h   0.000000   -2.160684   -1.270973
> h   0.000000   -2.160684    1.270973
> f   0.000000    0.000000   -2.742767
> h   0.000000    2.160684   -1.270973
> h   0.000000    2.160684    1.270973
> f   0.000000    0.000000    2.742767
> end}
> rhf;occ,8,2,5,1,7,2,4,;wf,58,1,0;
> save,2130.3
>
> multi;occ,9,2,6,1,8,2,4;closed,8,1,5,,7,1,4,;
> start,2130.3;
> wf,58,1,0;wf,58,3,0;wf,58,5,0;
> ccsd(t)
> eom,1.1,1.3,1.5
> put,molden,p-c6h4f2.molden;
> exit
>
> Can anyone please help me to resolve the problem?
>
> Thank you in advance.                                                 Rajagopala Reddy.Seelam
>


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Dr. Tatiana Korona http://tiger.chem.uw.edu.pl/staff/tania/index.html
Quantum Chemistry Laboratory
University of Warsaw
Pasteura 1, PL-02-093 Warsaw, POLAND


`The man who makes no mistakes does not usually make anything.'
                                        Edward John Phelps (1822-1900)