Simulation of Inelastic Neutron Scattering Spectra Directly from Molecular Dynamics Trajectories

Abstract

Inelastic neutron scattering (INS) is a widely used technique to study atomic and molecular vibrations. With the increasing complexity of materials and thus the INS spectra, being able to simulate the spectra from various atomistic models becomes an essential step and also a major bottleneck for INS data analysis. The conventional approach using density functional theory and lattice dynamics often falls short when the materials of interest are complex (e.g., defective, disordered, heterogeneous, amorphous, large-scale), for which molecular dynamics driven by an interatomic force field is a more common approach. In this paper, we demonstrate a method to directly convert molecular dynamics trajectories into simulated INS spectra, including not only fundamental but also higher order excitations. The results are compared with data collected on various representative samples from different neutron spectrometers. This development will open great opportunities by providing the key tool to perform in-depth analysis of INS data and to validate and optimize computer models.

Cation Dynamics and Structural Stabilization in Formamidinium Lead Iodide Perovskites

“…Experimental and theoretical spectra of FAPbI 3 (bottom panels) and MAPbI 3 (upper panels) calculated for the models presented in Figure S3 in the SI. ,− Fundamental transitions in the theoretical spectra are represented by thick lines. Different librational modes are depicted as colored insets, and assignments are labeled with Roman numerals.…”

Cation Dynamics and Structural Stabilization in Formamidinium Lead Iodide Perovskites

“…4 using PBE-D3(BJ) level of theory. [48][49][50][51][52][53][54] The contributions from the fundamental transitions in the theoretical spectra are represented by thick lines. Simplified visualization of different types of librational modes is provided as insets to the figure, with the experimental bands assigned with Roman numerals.…”

“…[56,57] Alternatively, we have also followed the recently implemented strategy to model the S (q,E ) spectra from MD trajectories by means of an approximate treatment of the Debye-Waller factor which accounts for overtone and combination bands as well the specific configuration of the TOSCA spectrometer. [54] More experimental and computational details are provided in the SI.…”

Joint neutron/molecular dynamics vibrational spectroscopy reveals softening of HIV-1 protease upon binding of a tight inhibitor

“…The INS spectra and vibrational density of states (VDOS) were calculated from the trajectories of hydrated protein powder MD simulations using the OCLIMAX program 67,71 and processed further using in-house python scripts where necessary. The velocity autocorrelation function (C (t) ) was calculated using eqn (1) for each atom to determine the statistical correlation of each atom over the timescale.…”