Table 1.
Comparison of Methods: Vertical low-lying singlet excited state energies (ΔE) in eV and oscillator strength (f) of G-C base pair calculated with the CC2/TZVP and ωB97XD/6–31G* methods (ε = 1).
| State | G-C base pair | |||
|---|---|---|---|---|
| CC2/TZVPa | ωB97XD/6–31G*b | |||
| Transition | ΔE(f) | Transition | ΔE (f) | |
| S1 | G(π) → G(π*) | 4.88 (0.061) | G(π) → G(π*) | 5.22 (0.0616) |
| S2 | C(π) → C(π*) | 5.06 (0.063) | C(π) → C(π*) | 5.32 (0.1036) |
| S3 | G(π) → C(π*) (CT)c | 5.23 (0.028) | G(π) → C(π*) (CT)c | 5.45 (0.0114) |
| S4 | C(n) → C(π*) | 5.49 (0.001) | C(n) → C(π*) | 5.72 (0.0010) |
| S5 | C(π) → C(π*) | 5.50 (0.183) | C(π) → C(π*) | 5.92 (0.1238) S6)d |
| S6 | G(π) → G(π*) | 5.51 (0.425) | G(π) → G(π*) | 5.75 (0.4124) (S5)d |
| S7 | C(n) → C(π*) | 5.80 (0.000) | C(n) → C(π*) | 6.45 (0.0001) (S8)d |
| S8 | G(n) → G(π*) | 5.90 (0.000) | G(n) → G(π*) | 5.94 (0.0005) (S7)d |