Dear Q-chem users and developers,
I want to calculate spin-flip TDDFT calculation on a combined system of C2 and C2H (having doublet spin symmetry in ground state) using Q-chem (5.4.0). I tried to do a restricted open-shell (ROKS) calculation on reference quartet state for further SF-DFT calculation. However, QChem showed the error “TDDFT based on ROKS is not available”.
Is there any other way I can do SF-TDDFT in Q-Chem starting from a ROKS reference calculation ? A part of the input file and the error message is attached herewith for your kind perusal.
Thanks in advance.
Regards,
Debroop
Input File:
$molecule
0 4
C -2.99885100 0.06836100 0.00006700
C -1.82163900 -0.02217400 -0.00007900
H -0.75857400 -0.10412700 -0.00009900
C 1.86005100 -0.19599300 0.00003500
C 3.08686700 0.16716100 -0.00000700
$end
$rem
JOBTYPE SP
SYMMETRY false
METHOD B3LYP
BASIS 6-31g**
CIS_N_ROOTS 6
!CIS_STATE_DERIV 1
SPIN_FLIP true
CIS_SINGLETS false
CIS_TRIPLETS false
unrestricted false
max_scf_cycles 200
MEM_TOTAL 200000
MEM_STATIC 2000
$end
Output File:
SCF time: CPU 29.02s wall 29.00s
<S^2> = 3.750000000
SCF energy in the final basis set = -152.5196979074
Total energy in the final basis set = -152.5196979074
Q-Chem fatal error occurred in module /home/debashree/Qchem5.3/qchem5.3/setman/setman_init.F, line 108:
TDDFT based on ROKS is not available