In a recent study of ours, we investigated the conformational behavior of a single oligomeric PTBT chain in solution by means of classical molecular dynamics (MD) simulations. Due to the conjugated nature of our system, one of the most important terms to be considered when evaluating the force field is the energetic profile governing the dihedral dynamics between neighboring monomers. The electro-polymerization of TBT monomers results in the formation of conjugated PTBT polymer chains. The polymerization of the five-membered heterocyclic thiophene ring can take place through bonding at the α-or β-positions (2or 3-positions, cf. Fig. ). In the TBT monomer, the β-position is substituted with a benzenethiol group. It is well established that the α-position is the most reactive position in the polymerization of 3-substituted thiophene monomers, leading to the dominance of α,α-linkages in the resulting polymer. As a result, the long PTBT polymer chains that form during polymerization will likely have thiophene rings as the main-chain backbones with benzenethiol groups as the lateral chains. 48-51 A key feature of the TBT monomer is the breaking of reflection symmetry between each end of the molecule (along the direction of the polymer backbone). This intrinsic asymmetry allows for three possible connections, head-to-head (HH), head-to-tail (HT), and tail-to-tail (TT), between two TBT repeat units (cf. Fig. ). The general terms 'head' and 'tail' distinguish the substituted groups at the β-positions of consecutive thiophene rings (here, the benzenethiol group is depicted as a head (H), and the hydrogen at the 4-position is the 'tail' (T)). For our system, we identify two critical dihedrals that will govern the aggregation behavior of the polymer chain. The backbone dihedral Θ b between the thiophene rings of neighboring TBT units (Fig. ) and the side chain dihedral Θ s between the thiophene ring and the benzenethiol group within one monomer (Fig. ). Details on the results of the re-parametrization and the validation of the optimized force field can be found in Table and Fig. -S5 of the SI.