Example: Numerical Frequencies of an excited state: PH2¶
Example for an excited state geometry optimization and frequency calculation.
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). The ground state and excited state are open shell.
$ADFBIN/adf <<eor TITLE PH2 Excited state geometry atoms P 0.000000 0.000000 0.0 H 0.7 0.0 0.7 H -0.7 0.0 0.7 end XC GGA BP86 END UNRESTRICTED CHARGE 0 1 BeckeGrid Quality good End GEOMETRY ITERATIONS 50 CONVERGENCE E=0.0001 grad=0.00001 END SCF converge 1.0e-9 END basis TYPE DZ CORE NONE end excitations LOWEST 10 onlysinglet end EXCITEDGO STATE B2 1 OUTPUT=1 end eor mv TAPE21 PH2.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 1’. Accurate SCF convergence parameters are used.
$ADFBIN/adf <<eor TITLE PH2 Excited state frequencies atoms P 0.000000 0.000000 0.002878 H 1.258230 0.000000 0.655775 H -1.258230 0.000000 0.655775 end XC GGA BP86 END UNRESTRICTED CHARGE 0 1 BeckeGrid Quality good End GEOMETRY FREQUENCIES END SCF converge 1.0e-9 END basis TYPE DZ CORE NONE end excitations LOWEST 10 onlysinglet end EXCITEDGO STATE A 1 OUTPUT=2 CPKS EPS=0.000001 end eor