# Example: Core excitation energies: TiCl4¶

Download TiCl4_CoreExci.run

Calculation of the 2p Ti and 2p Cl core excitation energies of TiCl4

The state selective method (key SELECTEXCITATION) can be used to calculate core excitation energies. The use of the key SELECTEXCITATION is similar as the use of the key MODIFYEXCITATION. However, the key SELECTEXCITATION can not be used in combination with the key MODIFYEXCITATION. In the state selective method (key SELECTEXCITATION) the one-electron excited state configuration space remains complete, whereas it is reduced in case the scheme with the MODIFYEXCITATION key.

First an example with the key MODIFYEXCITATION.

\$ADFBIN/adf << eor
Title TiCl4 TD-DFT scalar relativistic 2p Ti core excitations

Units
LENGTH BOHR
End

Atoms
Ti 0.       0.        0.
Cl    2.36754     2.36754     2.36754
Cl   -2.36754    -2.36754     2.36754
Cl    2.36754    -2.36754    -2.36754
Cl   -2.36754     2.36754    -2.36754
End
SYMMETRY T(D)

EPRINT
eigval 1000 1000
End

XC
GGA LB94
End

relativistic scalar zora

ModifyExcitation
UseOccupied
T2 2
SubEnd
UseScaledZORA
END

Excitation
ONLYSING
Davidson &
T2 12
SubEnd
End

Basis
Type DZ
Core None
End

BeckeGrid
Quality good
End

end input
eor


In this example, the 12 lowest singlet-singlet excitation energies of T2 symmetry are calculated, the dipole allowed excitations. This can also be achieved using the ALLOWED subkey in the key Excitation.

In this example only excitations from the 2t2 -orbital are included (see the key MODIFYEXCITATION), an almost pure 2p core orbital of titanium. The orbital energies of the uninteresting other occupied orbitals are artificially changed to a large negative value (-1d6 hartree).

In the second example the 2p Cl core excitation energies of TiCl4 are calculated. The difference between the first example in this one is mainly the use of the key MODIFYEXCITATION:

ModifyExcitation
UseOccRange -8.0 -6.0
UseScaledZORA
END


In this example only excitations from occupied orbitals are considered which have orbital energies between -8 and -6 hartree, namely the 5a1 , 1e, 1t1 , 4t2 , and 5t2 orbitals, which are almost pure 2p core orbitals of chlorine. The orbital energies of the uninteresting other occupied orbitals are again artificially changed to a large negative value (-1d6 hartree).

Another possibility is the use of the subkey OccVirtRange:

ModifyExcitation
UseOccVirtRange 7.0 100.0
UseScaledZORA
END


Similarly one can use the key SELECTEXCITATION.

SelectExcitation
UseOccupied
T2 2
SubEnd
UseScaledZORA
END

SelectExcitation
UseOccVirtRange 7.0 100.0
UseScaledZORA
END