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Here, we give some examples to perform spin-flip TDDFT calculation. You may find this input in $BDFHOME/tests/input/h2o_spinflip_TDDFT.inp | Here, we give some examples to perform spin-flip TDDFT calculation. |
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Tips: You may find this input in $BDFHOME/tests/input/h2o_spinflip_TDDFT.inp. |
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. We would like to calculate several triplet excited states using spin-flip TDDFT. Here is a input with comments. Notice: the words after # are comments. You may negelect them in your input.
$COMPASS Title H2O Molecule test run, cc-pvdz Basis cc-pvdz Geometry O 0.000000000 0.000000000 0.369372944 H 0.000000000 -0.783975899 -0.184686472 H 0.000000000 0.783975899 -0.184686472 End geometry Skeleton # You should not neglect this line. $END $XUANYUAN Direct # this line and the following line is important. Direct SCF is required. Schwarz $END $SCF RKS dft functional B3lyp $END # Spin flip up TDDFT calculation from RKS reference. $tddft imethod 1 # Starts from RKS calculation. 1 RKS, 2 UKS isf 1 # require spin flip up calculation idiag 1 itda 0 # TDDFT is evoked. iexit 4 # For each irreps, 4 states are required. $end # Spin flip up TDA calculation from RKS reference. $tddft imethod 1 # Starts from RKS calculation. 1 RKS, 2 UKS isf 1 # require spin flip up calculation idiag 1 itda 1 # TDA is evoked. iexit 4 # For each irreps, 4 states are required. $end
Tips: You may find this input in $BDFHOME/tests/input/h2o_spinflip_TDDFT.inp.