Benchmark on the bond length, frequency of the I–I bond and binding energy of molecular I2.
| Theoretical level | RI–I (Å) | FreqI–I (cm−1) | E b a (kcal mol−1) |
|---|---|---|---|
| Experimentb | 2.666 | 215.5 | −35.9 |
| CCSD(T)/dhf-QZVP | 2.659 | 224.4 | −44.9 |
| B3LYP-D3(BJ)/dhf-QZVP | 2.694 | 213.5 | −46.3 |
| B3LYP-D3(BJ)/def2-TZVPP | 2.688 | 214.1 | −46.5 |
| M06-2X/dhf-QZVP | 2.651 | 233.3 | −33.7 |
| M06-2X/def2-TZVPP | 2.652 | 232.5 | −33.8 |
a
Binding energy of I2 is defined based on the calculation of Eb = E(I2) − 2E(I), where E(I2) or E(I) suggests the corresponding single point energies.
b
Refer to the ref. 64.