While going through literature, I have seen that CASSCF method has been used to calculate the excitation energy of the first singlet state (S1 state). I too have tried it for some molecules. However, while trying to calculate for more than one excited state, the job gets terminated showing convergence error. I am trying to do it in Gaussian 16. I tried increasing the number of iterations, but still got the same error. This problem does not arise for the first singlet excited state. I have also tried various active spaces.
I am confused whether it is possible to study higher excited states using Gaussian.
Could someone please help me with this problem?
Commonly, to study excited state via CASSCF method you should use state-average treatment, if you ignored this point, please have a try. Also make sure that the choice of active space is reasonable.
As an example, the input files of CASSCF calculation for S0 to S3 states of benzene are attached. You should run HF.gjf first and then CASSCF.gjf.
Thank you for your reply. Once This is done, how will you go about finding the symmetry of the excited states? I have done a calculation for a molecule with Cs point group and following your method, i have obtained the energies. The configuration of S1 is 31, S2 is 8 and S3 is 4. I have the following in the output file
no. active orbitals (n) 8
no. active ELECTRONS (N)= 10
IRREPS TO BE RETAINED = 1 2
GROUP IRREP. MULT. TABLE
1 2
2 1
IRREP. LABELS FOR ORBITALS
1 1 1 1 1 1 1 1
BOTTOM WEIGHT= 30 TOP WEIGHT= 60
Configuration 1 Symmetry 1 11111000
Configuration 2 Symmetry 1 1111ab00
Configuration 3 Symmetry 1 11110100
Configuration 4 Symmetry 1 111a1b00
Configuration 5 Symmetry 1 1111a0b0
Configuration 6 Symmetry 1 111ab100
Configuration 7 Symmetry 1 11110ab0
Configuration 8 Symmetry 1 11a11b00
Configuration 9 Symmetry 1 111a10b0
Configuration 10 Symmetry 1 1111a00b
Configuration 11 Symmetry 1 11101100
Configuration 12 Symmetry 1 11a1b100
Configuration 13 Symmetry 1 111abab0
Configuration 14 Symmetry 1 11110010
Configuration 15 Symmetry 1 11110a0b
Configuration 16 Symmetry 1 1a111b00
Configuration 17 Symmetry 1 11a110b0
Configuration 18 Symmetry 1 111aabb0
Configuration 19 Symmetry 1 111a100b
Configuration 20 Symmetry 1 11ab1100
Configuration 21 Symmetry 1 11101ab0
Configuration 22 Symmetry 1 1a11b100
Configuration 23 Symmetry 1 11a1bab0
Configuration 24 Symmetry 1 111ab010
Configuration 25 Symmetry 1 111a01b0
Configuration 26 Symmetry 1 111aba0b
Configuration 27 Symmetry 1 111100ab
Configuration 28 Symmetry 1 a1111b00
Configuration 29 Symmetry 1 1a1110b0
Configuration 30 Symmetry 1 11a1abb0
Configuration 31 Symmetry 1 11a1100b
Configuration 32 Symmetry 1 111aab0b
How can i find the symmetry of the excited states?
- Badges
- Science topic
- Similar topics
- Correction