[molpro-user] How to calculate accurate spin-orbit splitting in sodium
Guenter Klatt
Guenter.Klatt at pci.uni-heidelberg.de
Fri Sep 13 13:38:32 BST 2013
Dear Molpro users,
I'm having a problem with the result of a simple test calculation on a sodium
atom. From my understanding the 2P state of sodium is split by spin-orbit
coupling, which leads to the famous Na doublet at 16,956 cm-1 and 16,973
cm-1,
i.e. a splitting by 17 wavenumbers.
My test calculation for the Na atom at CASSCF/MRCI levels yields splittings
of only 11.8 cm-1 (CAS) and 10.3 cm-1 (MRCI), respectively. Could you please
suggest ways of improving agreement with experiment? I have attached my input
file below.
Thanks very much for any help,
Gunter Klatt, University of Heidelberg
***,SO calculation for the Na atom
geometry={na}
basis={spd,na,vtz} !use uncontracted basis
{rhf;occ,3,1,1,,1;wf,11,1,1} !rhf for 2S state
{multi;occ,3,2,2,0,2 !casscf
frozen,0,0,0,0,0
closed,0,0,0,0,0
wf,11,1,1;wf,11,2,1;wf,11,3,1;wf,11,5,1} !2S and 2P states
{ci;wf,11,1,1;save,3042.1;noexc} !save casscf wavefunctions
{ci;wf,11,2,1;save,3062.1;noexc}
{ci;wf,11,3,1;save,3072.1;noexc}
{ci;wf,11,5,1;save,3082.1;noexc}
{ci;wf,11,1,1;save,4010.1} !mrci calculations for 2S state
{ci;wf,11,2,1;save,4042.1} !mrci calculations for 2P states
{ci;wf,11,3,1;save,4062.1} !mrci calculations for 2P states
{ci;wf,11,5,1;save,4082.1} !mrci calculations for 2P states
lsint !compute SO integrals
text,2P states, casscf
{ci;hlsmat,ls,3062.1,3072.1,3082.1;print,hls=2} !Only 2P states, casscf
text,2P states, mrci
{ci;hlsmat,ls,4042.1,4062.1;print,hls=2} !Only 2P states, mrci
text,2S, 2P states, casscf
{ci;hlsmat,ls,3042.1,3062.1,3072.1,3082.1;print,hls=2} !All states, casscf
text,2S, 2P states, mrci
ci;hlsmat,ls,4010.1,4042.1,4062.1;print,hls=2} !All states, mrci
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