Table 1. Geometries and the Dihedral Angles for the 21 Diatomic Molecules Used in the Present Benchmarking Seta.
| molecule | distance (Å) | angle (°) | dihedral (°) | ground state | FCI dim. |
|---|---|---|---|---|---|
| H2 | 0.7609 | 1Σ+ | (2e,10o) | ||
| LiH | 1.6136 | 1Σ+ | (4e,19o) | ||
| BeH | 1.3570 | 2Σ– | (5e,19o) | ||
| BH | 1.2551 | 1Σ+ | (6e,19o) | ||
| CH | 1.1424 | 2Σ– | (7e,19o) | ||
| NH | 1.9863 | 1Σ+ | (8e,19o) | ||
| OH | 0.9796 | 2Σ– | (9e,19o) | ||
| FH | 0.9200 | 1Σ+ | (10e,19o) | ||
| Li2 | 2.7139 | 1Σg+ | (6e,28o) | ||
| Be2 | 4.4269 | 1Σg+ | (8e,28o) | ||
| Li2 | 2.7139 | 1Σg+ | (2e,26o) | ||
| Be2 | 4.4269 | 1Σg+ | (4e,26o) | ||
| B2 | 1.6531 | 1Σg+ | (6e,26o) | ||
| C2 | 1.2728 | 1Σg+ | (8e,28o) | ||
| N2 | 1.1368 | 1Σg+ | (10e,16o) | ||
| O2 | 1.2786 | 3Σg– | (12e,16o) | ||
| F2 | 1.4186 | 1Σg+ | (14e,16o) | ||
| CH4 | 1.1015 | 109.5 | 120.0 | 1A1 | (8e,28o) |
| 240.0 | |||||
| NH3 | 1.0277 | 103.5 | 107.7 | 1A1 | (8e,28o) |
| H2O | 0.9668 | 101.9 | 0.0 | 1A1 | (8e,23o) |
| HF | 0.9203 | 1Σ+ | (8e,18o) |
a
The ground state is given in D∞h, C∞v, or the highest Abelian symmetry of the molecule.