# [molpro-user] Spin orbit coupling calculations

Rajagopala Reddy seelam srgreddyseelam at yahoo.co.in
Fri Oct 31 04:42:41 GMT 2008

```Dear Molpro Users,
I want to calculate Spin Orbit Coupling constant between  triplet sigma and singlet sigma of carbon monoxide dication.I am getting -0.55 cm- but the reported value is 120 cm-.The ground electronic state is triplet pi.Can you kindly tell me where i am doing wrong.I am giving the input for the calculation.How to analyse the output for the spin orbit calculations.

The input is as follows

***,co
print,basis,orbitals;
basis={spdf,c,vqz;spdf,o,vqz}
geomtyp=zmat
geometry={
bohr
C
O 1  r1}
end
r1=4
hf;wf,12,1,2;
!set,charge=2;
casscf;wf,12,1,0,state,2;
casscf;wf,12,4,2,state,2;
mrci;
MAXITER,126,126;
wf,12,1,0;
state,2;
save,4010.1;
mrci;
MAXITER,256,256;
wf,12,4,2;
state,2;
save,4042.1;
ci;hlsmat,ls,4010.1,4042.1;
put,molden,test5.molden;

The out put is as follows

Eigenvalues of the spin-orbit matrix
....................................

Nr  Sym         E             E-E0         E-E0           E-E(1)      E-E(1)      E-E(1)
(au)            (au)        (cm-1)           (au)       (cm-1)        (eV)
1   1   -111.66658284     -0.00000251       -0.55      0.00000000        0.00      0.0000
2   1   -111.56933678      0.09724355    21342.49      0.09724607    21343.04      2.6462
3   1   -111.52300718      0.14357315    31510.66      0.14357567    31511.22      3.9069
4   1   -111.51933886      0.14724147    32315.77      0.14724398    32316.32      4.0067

5   2   -111.66658033      0.00000000        0.00      0.00000251        0.55      0.0001
6   2   -111.51935394      0.14722639    32312.46      0.14722890    32313.01      4.0063

7   3   -111.66658033      0.00000000        0.00      0.00000251        0.55      0.0001
8   3   -111.51935394      0.14722639    32312.46      0.14722890    32313.01      4.0063

E0 =   -111.66658033 is the energy of the lowest zeroth-order state
E1 =   -111.66658284 is the energy of the lowest SO-state

Rajagopala Reddy.Seelam