[molpro-user] question on Cu example in the manual

[Jussi Eloranta]

Hi,

I noticed the following example in molpro manual:

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! $Revision: 2006.3 $
***,CU
! SCF d10s1 -> d9s2 excitation energy of the Cu atom
!  using the relativistic Ne-core pseudopotential
! and basis of the Stuttgart/Koeln group.
gprint,basis,orbitals
geometry={cu}
basis
ECP,1,10,3;   ! ECP input
  1; ! NO LOCAL POTENTIAL
  2,1.,0.;
  2; ! S POTENTIAL
  2,30.22,355.770158;2,13.19,70.865357;
  2; ! P POTENTIAL
  2,33.13,233.891976;2,13.22,53.947299;
  2; ! D POTENTIAL
  2,38.42,-31.272165;2,13.26,-2.741104;
! (8s7p6d)/[6s5p3d] BASIS SET
s,1,27.69632,13.50535,8.815355,2.380805,.952616,.112662,.040486,.01;
c,1.3,.231132,-.656811,-.545875;
p,1,93.504327,16.285464,5.994236,2.536875,.897934,.131729,.030878;
c,1.2,.022829,-1.009513;C,3.4,.24645,.792024;
d,1,41.225006,12.34325,4.20192,1.379825,.383453,.1;
c,1.4,.044694,.212106,.453423,.533465;
end
rhf;
e1=energy
{rhf;occ,4,1,1,1,1,1,1;closed,4,1,1,1,1,1;wf,19,7,1;}
e2=energy
de=(e2-e1)*toev  ! Delta E = -0.075 eV

---

This looks a bit odd since it claims that the ^2D is lower than ^2S 
(which should be the ground state). Further more, I got a bit curious 
because of this example and ran mcscf with 3d and 4s in the active space 
and that gives completely wrong answers as well as it also claims that 
the ^2D is lower than ^2S. If one adds CISD on top of this
the situation is corrected somewhat (the energy order becomes correct 
but the gap is now too high by over 0.5 eV). This behavior shows up all 
the way to av5z (-> not a basis set issue). Including SO is not going to 
help out (tried that).

So, two things: a) the example in the manual is perhaps not a good one 
and b) any idea why Cu atom seems to be such a tough case?


Sincerely,

Jussi Eloranta
Department of chemistry & Biochemistry
Cal State Northridge