Computer Simulation of Long Side‐Chain Substituted Poly(phenylene vinylene) Polymers

Abstract

A molecular dynamics (MD) simulation was employed to investigate structure features and segment orientation of four poly (phenylene vinylene) (PPV) derivatives with long, flexible side chains at room temperature. In the simulations, the main chains of the polymers were found to be semirigid and exhibit a tendency to coil into ellipsoidal helices or form zigzag conformations of limited regularity. The simulations show that continuous quasi-coplanar segments along the backbone are in a range of approximately 2-4 repeat units. The ordered orientation and coupling distance of interchain aromatic rings can be correlated with optical properties of materials. A simplified quantum-mechanical method was developed to investigate optical properties based on MD trajectories. The method was tested to simulate the absorption spectra of four PPV derivatives. The absorption maxima of the calculated spectra are in reasonable agreement with experimental data. This work implies that long-range electron transfer along the backbones of these polymers may not occur, but may be mediated by interchain interactions.

Theoretical investigations of electronic structure and charge transport properties in polythiophene‐based organic field‐effect transistors

“…We also employed molecular dynamics (MD) with a PCFF (polymer consistent force field)24 to simulate the equilibrated P3HT structures at regularity equal to 100% and room temperature in a given packing state. In the simulation of the packing state, the system contains 4 P3HT molecules with 64 thiophene rings per chain and each P3HT molecule is artificially set as an infinite chain25 to avoid the influence of the end group libration. Initially, the 4 P3HT molecules were set to form a lamellar structure with an inter‐chain separation distance of 4.0 and 17 Å along the π−π stacking and side‐chain packing directions, respectively.…”

Molecular dynamics simulations of AP/HMX composite with a modified force field

“…According to the ratio of mass (1:1), 20 AP molecules and 48 HMX molecules were placed in a cubic box and the total number of atoms is 2544. As is suggested in the literatures [46,47], we started our NVT MD simulation at a low density of 0.1 g/cm 3 until it reached thermal equilibrium at room temperature. After that, the MD run was carried out for another 100 ps to ensure that the system was truly in the thermal equilibrium condition.…”

The role of disorder on the electronic structure of conjugated polymers. The case of poly-2,5-bis(phenylethynyl)-1,3,4-thiadiazole

“…This step is followed by an equilibration over 300 ps at constant volume and a final relaxation to a local minimum. This protocol, similar to other MD-based methods used for the generation of amorphous atomic structures, 27,28 allows the system to explore a significant amount of conformational Table 1 A list of the atom types and charge density motifs used for the charge patching of PhEtTh a…”