Computing inelastic neutron scattering spectra from molecular dynamics trajectories

Inelastic neutron scattering (INS) provides a weighted density of phonon modes. Currently, INS spectra can only be interpreted for perfectly crystalline materials because of high computational cost for electronic simulations. INS has the potential to provide detailed morphological information if sufficiently large volumes and appropriate structural variety are simulated. Here, we propose a method that allows direct comparison between INS data with molecular dynamics simulations, a simulation method that is frequently used to simulate semicrystalline/amorphous materials. We illustrate the technique by analyzing spectra of a well-studied conjugated polymer, poly(3-hexylthiophene-2,5-diyl) (P3HT) and conclude that our technique provides improved volume and structural variety, but that the classical force field requires improvement before the morphology can be accurately interpreted.

Automated summary

Inelastic neutron scattering provides weighted density of phonon modes and has the potential to offer detailed morphological information. Researchers have proposed a method for direct comparison between INS data and molecular dynamics simulations, but improvements are needed in the classical force field for accurate interpretation of morphology.