Table 2. Forward and reverse activation energies at 0 K of the steps of Scheme 1 in unconfined space and CHA voids at DFT-PBE and Grimme-D2 (Quantum Espresso).
| E f,gas [kJ mol–1] | E f,CHA [kJ mol–1] | E b,gas [kJ mol–1] | E b,CHA [kJ mol–1] | |
| NO + NO → trans-ONNO (step 1.1) | 0.0 | 0.0 | 62.7 | 62.7 |
| trans-ONNO + O2 → cis-NOO2NO (step 1.2) | 1.0 | 1.0 | 70.4 | 73.3 |
| cis-NOO2NO → trans-NOO2NO (step 1.3) | 39.6 | 40.5 | 45.3 | 47.3 |
| trans-NOO2NO → ONOONO (step 1.4) | 9.6 | 8.7 | 93.6 | 97.5 |
| ONOONO → cis-ONONO2 (step 1.5) | 37.6 | 39.6 | 53.1 | 48.2 |
| cis-ONONO2 → trans-ONONO2 (step 1.6) | 34.7 | 29.9 | 24.1 | 21.2 |
| trans-ONONO2 → O2NNO2 (step 1.7) | 68.5 | 78.2 | 131.2 | 139.9 |
| O2NNO2 → 2NO2 (step 1.8) | 158.2 | 158.2 | 0.0 | 0.0 |