Example: Spin-flip excited state geometry optimization: CH2¶
Example for a spin-flip excited state geometry optimization with a triplet reference, and a frequency calculation afterwards.
Needed for such excited state optimizations are the key EXCITATIONS (to calculate excitation energies), the key GEOMETRY (to do a geometry optimization) and the key EXCITEDGO (to select for which excitation a geometry optimization should be performed). In this case spin-flip excitations are calculated.
$ADFBIN/adf <<eor TITLE CH2 Excited state geometry with triplet reference and spin-flip excitation atoms C 0.000000 0.000000 0.0 H 0.7 0.0 0.7 H -0.7 0.0 0.7 end UNRESTRICTED CHARGE 0 2 GEOMETRY ITERATIONS 50 CONVERGENCE E=0.0001 grad=0.0001 END basis TYPE DZP CORE NONE end excitations LOWEST 10 end TDA SFTDDFT FORCEALDA EXCITEDGO STATE B2 1 OUTPUT=2 end SYMMETRY C(2V) eor mv TAPE21 CH2.t21
Next the frequencies are calculated of the excited state. A restart is used to pick up the excited state geometry of the previous calculation. Note that in a numerical FREQUENCIES calculation symmetry is turned off except to reduce the number of points calculated. Thus irrespective of the specified point group symmetry the symmetry label A of SYMMETRY NOSYM should be used to select the excited state. Care should be taken to ensure that the correct state is chosen in this frequencies calculation as the excited state number can change when the point group is changed. In this case instead of ‘B2 1’ one needs to select ‘A 2’.
$ADFBIN/adf <<eor TITLE CH2 Excited state frequencies with triplet reference and spin-flip excitation atoms C 0.000000 0.000000 0.0 H 0.7 0.0 0.7 H -0.7 0.0 0.7 end RESTART CH2.t21 UNRESTRICTED CHARGE 0 2 GEOMETRY FREQUENCIES END basis TYPE DZP CORE NONE end excitations LOWEST 10 end TDA SFTDDFT FORCEALDA EXCITEDGO STATE A 2 OUTPUT=2 end SYMMETRY C(2V) eor