Figure illustrates the results of top-down energy screening applied to a test set of (H 2 O) 20 clusters at the MBE(3) and MBE(4) levels. The top-down method requires a screening procedure at each n-body level, for which we use GFN2-xTB with a three-body threshold τ 3 ranging from τ 3 = 0 (meaning no screening) up to 0.15 kcal/mol. For simplicity, the four-body threshold (τ 4 ) is set to τ 4 = α τ 3 , for α = 0.05, 0.10, or 0.20. Larger values of τ n indicate more aggressive screening, resulting in fewer subsystems. Throughout this work, error is defined as