Fig. 2
Ab intio information processing and model extraction. a The ab initio linear vibronic Hamiltonian describes how each vibration mode of frequency ωi (outer circles) couples to the system (S). The coupling matrix for each mode could be different, shown as the colour of connecting lines. b A K-means learning (clustering) algorithm groups modes according to their common coupling type (colour grouping in figure). c A unitary transform (linear combination of vibration modes) of each cluster creates an equivalent nearest-neighbour chain representation of the Hamiltonian, ideal for tensor network simulation
