TD-DFT is possible to calculate excited state that has different spin with the reference state. Here, we give some examples for such calculation.

Some important issues

Integral direct TDDFT

Since TDDFT is a capable to study medium to large molecules, so called integral-direct method is preferred in TD-DFT calculation. To apply integral-direct TDDFT, integral-direct SCF should be evoked that fully avoids to store electronic repulsive integrals in disk. Thus, molecules with several tens or even hundred of atoms are possible via TDDFT calcualiton.

Examples of spin-flip TDDFT

Here, we give some examples to perform spin-flip TDDFT calculation.

Spin-flip TDDFT to calculate triplet state of H2O molecule

We start from ground state of H2O. It is a close shell ^1A1 state.