Neutron spectroscopy as a method for classical force-field parameterization: Past methods, present successes and future challenges

Classical molecular dynamics (MD) plays a central role in understanding structural and dynamical phenomena across all disciplines of physical chemistry. These models can be used to interpret experimental data, or as a method of study in their own right. Their legitimacy however rests solely on the accuracy of the underlying force-field, and so the parameterisation of these force-fields is the most crucial aspect of any study. The typical methods of parameterisation are structural or thermodynamic in nature, however this perspective article will examine a little used metric of parametersation; that of neutron spectroscopy, and in particular quasi-elastic neutron spectroscopy (QENS). QENS data contains self-correlation information for the hydrogen atoms of a system, over a wide range of distances and time-scales. These scales are relevant for local and global diffusion and rotation, thus pairing very well to the scales of molecular dynamics for organic systems. This article focuses in particular on the parameterisation of models of porous and surface catalysts. This area is a particularly rich field for the application of QENS, however there is a distinct lack of accurate classical force-fields currently.