The initial rise of dephasing curves for multi-spin systems are well-represented by two-spin numerical simulations when the dipolar coupling constant is replaced by 0𝐷 $%& " . Since the dipolar coupling constant is small when the 1 H- Cl distance > 5 Å (DHCl < 94 Hz), 0𝐷 $%& " can be used to add in the long-range 1 H- Cl dipolar interactions because we will only observe the intial rise of the dipolar dephasing curve when the total dipolar recoupling duration is ca.12 ms. 0𝐷 $%& " was determined to be 94, 85 or 90 Hz for the models with a 5, 6 or 7 Å Si-Si interlayer spacing, respectively. This two-spin numerical simulation was added to the averaged multi-spin numerical simulation discussed above to obtain the final simulated dephasing curve. Note, the long-range correlation correction only effects the extent of dephasing at long recoupling durations (Figure ). The initial rise of the experimental dephasing curve (up to ca. 4 ms) is well-represented by the muli-spin numerical simulations that included all 1 H- Cl spins within a distance of ≤ 5 Å (Figure ).