[molpro-user] FCI calculation

[rama chandran]

Dear Molpro users,
I did one molpro calculation for a triatomic linear
system containing 3 electron  HeH2+ linear.
Earlier the energy for this system was reported to be 


        MRCI            CASSCF          HF-SCF  
     -3.51818587     -3.48901389     -3.47036561

using th input 


 ***,HeH2plus
  Memory,100,M
  geometry={H;
  H1,H,r1;
  He,H,r2,H1,a1}
   r1=2.075338
   r2=1.931059
   a1= 180.0
  basis=v5Z
 {HF
 occ,2,0,0,0
 wf,charge=1,symmetry=1,spin=1
 }
 casscf
 mrci


I tried to redo the problem using  Full-CI
calculations
I tried it in 3 different ways as I have not done any
full CI calculations before...
when I tried with the keyword fci alone without
specifying anything else it terminated with the error
saying that orbital record not found.
Then I specified the wavefunction details as above,
still the same error.
Then I did the fci followed taking  previous hf
wavefunction   and also another calculation in which
fci taking casscf wavefunction as follows, 

***,HeH2+intermediate-example-FCI
 memory,50,m
 geometry={H;
  H1,H,r1;
  He,H,r2,H1,a1}
   r1=2.075338
   r2=1.931059
   a1= 180.0
 basis,H=v5z
 !define basis
 hf
 {fci
 occ,2,0,0,0
 wf,charge=1,symmetry=1,spin=1
 }



and 


***,HeH2+intermediate-example-FCI
 memory,50,m
 geometry={H;
  H1,H,r1;
  He,H,r2,H1,a1}
   r1=2.075338
   r2=1.931059
   a1= 180.0
 basis,H=v5z                                          
                       
{casscf
 occ,2,0,0,0
 wf,charge=1,symmetry=1,spin=1
 }
 {fci
 }

both gives the same energy as -3.50605528 Hartrees

As you see this energy is very much different from the
values they reported through MRCI calculations....
I was expecting a lower energy through full CI
calculations.  Is something wrong....??

Can anyone advice me with some details?


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