Example: TDHF excitation energies: N2¶
Calculation of the excitation energies of N2 using time-dependent Hartree-Fock (TDHF). It also shows the possibility to use the Tamm-Dancoff approximation (TDA). This examples consists of 4 calculations:
- non-relativistic TDHF
- spin-orbit coupled TDHF
- non-relativistic TDHF, TDA
- spin-orbit coupled TDHF, TDA
The results will be inaccurate due to small basis set. The key ADDDIFFUSEFIT is required for a more accurate fit of the density.
$ADFBIN/adf << eor Atoms N 0 0 0 N 0 0 1.0977 End XC hartreefock end dependency bas=1e-4 adddiffusefit Basis Type DZ Core None End BeckeGrid Quality Good End excitations lowest 5 end End Input eor
In case of spin-orbit coupling one needs to include the key RELATIVISTIC with argument ZORA SPINORBIT. In practice one needs to calculate more excitations if one includes spin-orbit coupling, since the singlet-singlet and singlet-triplet excitations are not calculated separately, but will be treated simultaneously, since they may mix.
excitations lowest 20 end relativistic spinorbit zora
The Tamm-Dancoff approximation (TDA) will be used if one includes the key TDA. The calculation is then effectively a CIS calculation.