Example: sTDA excitation energies wB97: TCNE-Benzene¶

Download TCNE-Benzene_wB97.run

Calculation of the excitation energies of the complex TCNE-Benzene using the simplified Tamm-Dancoff (sTDA) method by Grimme, for a range-separated function. This method is meant for hybrid functionals or range-separated functionals during the SCF. In this example the range-separated functional \(\omega\) B97 (wB97) is used during the SCF. In the the calculation of the excitation energies the sTDA method is used in which the required integrals are approximated. For range-separated functional one needs to set the parameters manually. Note that the alpha and beta parameters for sTDA for range separated functionals in the Risthaus paper (dx.doi.org/10.1039/C3CP54517B) are mixed up. A TZP or TZ2P basis set is recommended for this method.

First the atoms are calculated. To calculate this range-separated functional wB97 the RIHARTREEFOCK method is required, and LibXC is needed. For speed reasons the atoms are calculated separately, such that these calculations might run in parallel. If the BASIS key is used the atoms are calculated serially.

for n in H C N
do
$ADFBIN/adf << eor
Create $n file=$ADFRESOURCES/DZ/$n
XC
 LibXC wB97
End
RIHARTREEFOCK
 useme true
End
End Input
eor
mv TAPE21 $n.t21
rm logfile
done

Next the excitation energies of the complex TCNE-Benzene are calculated, in which charge transfer states are important. Symmetry NOSYM is required. The sTDA parameters should be set with the subkeys GRIMMEAEX, GRIMMEALPHA, and GRIMMEBETA of the key MODIFYEXCITATION.

$ADFBIN/adf << eor
Atoms
C     -2.274205   -1.398789   -0.000000
C     -2.274206    1.398791   -0.000000
C     -2.274506   -0.699551    1.213150
C     -2.274505   -0.699551   -1.213150
C     -2.274506    0.699551    1.213150
C     -2.274505    0.699551   -1.213150
H     -2.278385   -2.491323   -0.000000
H     -2.278386    2.491321   -0.000000
C      1.368996   -0.686302    0.000000
C      1.368996    0.686301    0.000000
C      1.379968   -1.434052   -1.220900
C      1.379968   -1.434052    1.220895
C      1.379968    1.434051   -1.220900
C      1.379967    1.434051    1.220895
N      1.400955   -2.054479   -2.204820
N      1.400955   -2.054479    2.204824
N      1.400955    2.054481   -2.204820
N      1.400954    2.054481    2.204824
H     -2.276046   -1.246672    2.158733
H     -2.276045   -1.246672   -2.158730
H     -2.276045    1.246671   -2.158730
H     -2.276046    1.246671    2.158733
End
Fragments
 H H.t21
 C C.t21
 N N.t21
End
symmetry nosym
excitations
 stda
 onlysing
end
RIHARTREEFOCK
 useme true
end
XC
 LibXC wB97
END
modifyexcitation
 GRIMMEPERTC
 GRIMMEAEX   0.61
 GRIMMEALPHA 4.41
 GRIMMEBETA  8.00
end
End Input
eor