Pair-wise bonded interactions: We illustrate the challenges using bond order calculations as an example. As shown in Fig. , all bonded interactions depend on the corrected bond order term. Initially, if the distance between two atoms is less than a given cutoff, typically 5 Å, the uncorrected bond orders (BO) are calculated according to Eq. ( ), where r ij is the distance between the atom pair i-j, and p bo1-6 , r σ o , r π o , and r ππ o are the corresponding parameters.