[molpro-user] Calculation for excited Ne+

[Terry Frankcombe]

Why not simply do the RHF for the neutral, then start selecting configs
for the CI?

Converging the core hole state should certainly be possible.  But it may
require a largish multi-state CI.  (Speaking off the top of my head
here.)


On Mon, 2013-05-06 at 17:25 +0100, Lorenzo Lodi wrote:
> I would like to compute the energy (using Hartree-Fock and then
> configuration interaction) of an excited state of the Ne+ atomic ion
> with configuration  (1s)^1 (2s)^2 (2p)^6.
> I tried
> {UHF; WF,nelec=9,symmetry=1,spin=1; occ,2,1,1,0,1; open, 1.1; ORBPRINT,0}
> 
> which seems to work, and produces approximately the correct energy
> (about 31 hartrees above the ground state of Ne+).
> On the other hand, the same input using RHF
> {RHF; WF,nelec=9,symmetry=1,spin=1; occ,2,1,1,0,1; open, 1.1; ORBPRINT,0}
> 
> converges to the ground state, as if the `open, 1.1' command was
> ignored. However, if I do UHF and then RHF using UHF orbitals as
> starting guess then RHF also goes to the correct state. Any comments?
> 
> When I try to use the RHF orbitals for MRCI ( CISD in this case)
> {MRCI; WF,nelec=9,symmetry=1,spin=1; STATE,1}
> 
> I get the error message:
> CI VECTOR FOR STATE 1 DOES NOT OVERLAP SUFFICIENTLY WITH REFERENCE VECTORS
> It may help to increase NSTATI, e.g., use OPTION,NSTATI=2
> 
> Setting NSTATI=2 gives the error
> MORE STATES THAN REFERENCE CONFIGURATIONS:     2    1
> 
> 
> What can I do to have MRCI to converge on the correct state?
> 
> Lorenzo
> 
> 
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