Essentials of Computational Chemistry

14.4 SUM AND PROJECTION METHODS 503
Table 14.3 Vertical excited-state energies (eV) of 4-dimethylaminobenzonitrile and 3,5-dimethyl-
4-dimethylaminobenzonitrile relative to S0 ground state
NC N
Method S1 ( 1 B, local) S2 ( 1 A, CT) T1 ( 3 A, CT) T2 ( 3 B, local)
CASPT2/DZP b 4.05 4.41 3.66 3.69
B3LYP-MRCI/TZVP a 4.33 4.62
B3LYP-SCI/DZVP c 4.1 4.6 3.12 3.51
TD-LSDA//AM1 d 3.89 4.17 3.10 3.43
LSDA//AM1 SCF d 3.27
TD-B3LYP//AM1 d 4.38 4.54 3.10 3.73
B3LYP//AM1 SCF d 3.32
TD-PBE1PBE//AM1 d 4.49 4.64
TD-LSDA d 3.92 4.26 3.12 3.40
LSDA SCF d 3.29
TD-B3LYP d 4.38 4.62 3.14 3.68
B3LYP SCF d 3.35
Experiment e 4.25 4.56 3.36 3.50
NC N
Method S1 (CT) S3 (local) T1 (CT) T2 (local)
B3LYP-SCI/DZVP+ e 4.17 4.95 3.77 4.03
TD-B3LYP d 3.91 4.98 3.08 3.94
B3LYP SCF d 3.38
TD-PBE1PBE d 4.09 5.16 3.02 4.01
PBE1PBE SCF d 3.37
TD-mPW1PW91 d 4.10 5.16 3.00 4.04
mPWPW91 SCF d 3.37
Experiment e 4.27 5.00 3.48 4.31
a Parusel (2000).
b Serrano-Andrés et al. (1995).
c Parusel, Köhler, and Grimme (1998).
d Jamorski et al. (2002); 6-311+G(2d,p) basis set.
e Bulliard et al. (1999).
(2002) and some of their results are summarized in Table 14.3. An observation made in all
of the above studies, and one that is particularly important for future developmental efforts,
is that the TDDFT methodology performs relatively poorly for excitations characterized as
charge-transfer (CT) or charge-resonance in weakly interacting composite chromophores (see
also Casida et al. 2000 and Zyubin and Mebel 2003). Note, though, that the SCF approach
works well when it is possible to employ it.
Efforts to improve TDDFT for higher-energy excitations have shown some early success.
Tozer and Handy (1998) have proposed a correction procedure to deliver functionals having
CH 3
CH 3
CH 3
CH3
CH 3
CH 3