[molpro-user] FCI calculation
rama chandran
rcchelat at yahoo.co.in
Tue Jan 29 11:40:46 GMT 2008
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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