where ∆r i × f i (r n ), on the FG particles comprising each of the N CG particles in each of the same t FG configurations. As the matrix generally contains many rows compared with the number of columns, it is beneficial to apply prior sequential QR factorizations to transform it into square form to reduce the computational cost of producing the least-squares solution. After finding the optimal parameter set λ, the CG potential U (R N , Ω N ; λ) can be reconstructed using Eq. ( ), from which forces and torques can be calculated for use in dynamical simulations.