Nuclear Induction Lineshape Modeling via Hybrid SDE and MD Approach

TL;DR

This paper introduces a hybrid SDE-MD modeling approach to accurately predict nuclear induction lineshapes in gases, accounting for temperature effects, boundaries, and complex environments, aligning well with experimental data.

Contribution

The paper presents a novel hybrid stochastic differential equation and molecular dynamics method for lineshape modeling, incorporating boundaries and complex interactions.

Findings

Model accurately predicts temperature-dependent lineshapes.

Method agrees with experimental observations.

Bridges molecular-scale dynamics with nuclear induction phenomena.

Abstract

The temperature dependence of the nuclear free induction decay in the presence of a magnetic-field gradient was found to exhibit motional narrowing in gases upon heating, a behavior that is opposite to that observed in liquids. This has led to the revision of the theoretical framework to include a more detailed description of particle trajectories, since decoherence mechanisms depend on histories. In the case of free diffusion and single component, the new model yields the correct temperature trends. Inclusion of boundaries in the current formalism is not straightforward. We present a hybrid SDE-MD (stochastic differential equation - molecular dynamics) approach whereby MD is used to compute an effective viscosity and the latter is fed to the SDE to predict the lineshape. The theory is in agreement with experiments. This two-scale approach, which bridges the gap between short (molecular collisions) and long (nuclear induction) timescales, paves the way for the modeling of complex environments with boundaries, mixtures of chemical species and intermolecular potentials.