The correlation lengths obtained by evaluating the GPR models are similar to those obtained directly from the input data, but they are slightly If low noise is assumed for Ni, the correlation length drops to ∼2 degrees. See Table for GPR parameters for each dataset. By contrast, if a GPR model is trained on a large set of 50 000 GBs sampled from the Bulatov Reed Kumar (BRK) model, the numerically optimized correlation length is 10.5°suggesting that the BRK model imposes apriori information that GBs are more correlated than the data warrants. In other words, the BRK function is too smooth.