 ## Firefly and PC GAMESS-related discussion club

Learn how to ask questions correctly  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
Ā 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   This message read 448 times