Akin to model C, the coupling layers in a model H were trained to flatten the configurational distribution of the MD data, to map it as close as possible to a uniform distribution over z H (Fig. ). In terms of achieving a uniform distribution of rotations, this corresponds to uniformly sampling the surface of the hemisphere of S 3 . For this reason model H transforms s back to q * on both sides of the flow, including the noisy side (Fig. ). The log base distribution ln p 0 in model H was therefore set to: