This keyword sets the number of neurons in the hidden layer of the NN. The syntax is:

neuron <number_of_neurons>

where <number_of_neurons> corresponds to \(N_\mathrm{neu}\) in the NEP formalism [Fan2022b]. Values must satisfy \(1 \leq N_\mathrm{neu} \leq 200\).

The default value is 30, which is relatively small but can lead to relatively high speed. Larger values rarely lead to a notable improvement.