The pairwise mutual information terms between all pairs of degrees of freedom in butane computed using the first (A) 4 ns, (B) 10 ns, (C) 25 ns, or (D) 50 ns are show in the lower triangles. The upper triangles indicate the terms that were chosen to be included in the second-order MIST approximation, according to Eq. (7). The dark blue lines separate the atoms from each other, with each atom being represented by three degrees of freedom associated with its placement (bond, angle, torsion from bottom to top and left to right in each box). All values are reported in kcal/mol.