Fig. 3: Convergence of Hamiltonian and overlap blocks with respect to the order and maximum degree of the ACE basis set.

a Onsite Hamiltonian blocks HII fitted with order 2 models of varying maximum degree. b Offsite Hamiltonian blocks with order 1 ACE models. c Offsite Hamiltonian blocks with order 2 ACE models. In all plots solid lines show errors on training data and dashed lines errors on test data. Colours match the block structure of Fig. 2. Note the distinct markers that distinguish the non-adjoint entries in the offsite Hamiltonian and overlap blocks.