Chemistry Reference
In-Depth Information
Table 5
Performance of Wave Function Methods for Excitations of Table 4
Method
1
1
B
3
u
1
1
B
2
u
2
1
A
g
1
1
B
1
g
2
1
B
3
u
1
1
A
u
CIS
a
5.139
4.984
7.038
6.251
6.770
5.862
CC2
a
4.376
4.758
6.068
5.838
6.018
5.736
CASPT2
b
4.03
4.56
5.39
5.53
5.54
5.54
Expt.
3.97, 4.0
4.45, 4.7
5.50, 5.52
5.28, 5.22
5.63, 5.55 5.89
''best''
b
4.0
4.5
5.5
5.5
5.5
5.7
a
The aug-TZVP basis set and the PBE/TZVP/RI ground-state structure was used.
b
CASPT2 results and experimental results are from Ref. 200.
the excited-state structure differs significantly from the ground-state structure.
For the lower valence states, the CASPT2 results can therefore be expected to
be at least as accurate as the experimental data. For higher excited states, the
basis set used in the CASPT2 calculations appears rather small, and the
approximate second-order coupled-cluster values denoted RICC2
213-215
might be a better reference with which to make comparisons. Thus, our best
guess (denoted ''best'' in the tables) is from experiment for the first four tran-
sitions, CASPT2 for the fifth transition, and RICC2 for the sixth transition.
We begin with some general observations:
1. The excitation energies predicted by the GGA functionals BP86 and PBE
differ marginally from the LSDA results (an exception being the 1
1
A
u
Rydberg state, whose PBE excitation energy is substantially lower than
those of all other methods). Note, however, that GGA functionals generally
improve the results compared to LSDA results for other excited-state
properties such as structures or vibrational frequencies.
Table 6
Performance of Density Functional and Correlated
Wave Function Methods for Oscillator Strengths of First Three
Dipole-Allowed Transitions of Naphthalene
Method
a
1
1
B
3
u
1
1
B
2
u
2
1
B
3
u
LSDA 0.0000 0.0405 1.1517
BP86 0.0000 0.0411 1.1552
PBE 0.0000 0.0407 1.1402
B3LYP 0.0000 0.0539 1.2413
PBE0 0.0000 0.0574 1.2719
LHF/LSDA 0.0000 0.0406 1.2089
LHF/PBE 0.0000 0.0403 1.2008
CIS 0.0002 0.0743 1.8908
CC2 0.0000 0.0773 1.4262
CASPT2 0.0004 0.0496 1.3365
expt. 0.002 0.102, 0.109 1.2, 1.3
a
An aug-TZVP basis set and the PBE/TZVP/RI ground-state structure
was used for all except the CASPT2 results, which were taken from
Ref. 200.
