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** Spin-orbit couplings only between states of consecutive CI calculations? **
Bernhard Dick

bernhard.dick@chemie.uni-regensburg.de

Dear Alex,

I want to calculate the SOC between the singlet and triplet states of biphenylene. The molecule has D2 symmetry. I made orbitals by MCSCF with 12 electrons in 12 orbitals (i.e. full pi-space), then use these orbitals for the CI calculations. When I switch off symmetry and do one calculation each for singlets and triplets, the CI "overlooks" the singlet state #4. Therefore, and for an easier symmetry assignment, I used one CI for each irreducible representation, i.e.

$CIDRT1 GROUP=D2 ISTSYM=1 NMCC=35 NDOC=6 NALP=0 NVAL=6 FORS=.T. $END

$CIDRT2 GROUP=D2 ISTSYM=2 NMCC=35 NDOC=6 NALP=0 NVAL=6 FORS=.T. $END

$CIDRT3 GROUP=D2 ISTSYM=3 NMCC=35 NDOC=6 NALP=0 NVAL=6 FORS=.T. $END

$CIDRT4 GROUP=D2 ISTSYM=4 NMCC=35 NDOC=6 NALP=0 NVAL=6 FORS=.T. $END

$CIDRT5 GROUP=D2 ISTSYM=1 NMCC=35 NDOC=5 NALP=2 NVAL=5 FORS=.T. $END

$CIDRT6 GROUP=D2 ISTSYM=2 NMCC=35 NDOC=5 NALP=2 NVAL=5 FORS=.T. $END

$CIDRT7 GROUP=D2 ISTSYM=3 NMCC=35 NDOC=5 NALP=2 NVAL=5 FORS=.T. $END

$CIDRT8 GROUP=D2 ISTSYM=4 NMCC=35 NDOC=5 NALP=2 NVAL=5 FORS=.T. $END

$GUGDIA ITERMX=2000 cvgtol=1d-7 $END

$transt numvec=1 numci=8 nfzc=35 nocc=47 iroots(1)=2,2,2,2,2,2,2,2

CASTRF=.T. $end

However, Firefly now calculated coupling coefficient only within one CI, and with the following CI. E.g., within the CI#1 (singlet A-states) and between CI#1 (singlet-A) and CI#2 (singlet B1), but not between CI#1 and CI#6 (triplet B1 states) etc.

So what am I doing wrong?

with best regards,

Bernhard

Wed Jul 25 '18 1:15am

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