Feedforward Neural Network (NN) These can generate nonlinear relationships between input and output variables and adaptively learn highly complex relationships. The input layer receives the descriptor vector, the hidden layers composed of a number of neurons perform nonlinear computation, and the output layer generate the response variable. We used a fully connected network where each neuron in a layer is connected to all neurons in the previous later. Each neuron operates on a weighted sum of the data it receives from the elements of the previous layer using an activation function i.e.