Intermediate scattering function

In condensed matter physics, the dynamic structure factor is a mathematical function that contains information about inter-particle correlations and their time evolution. It is a generalization of the structure factor which considers correlations in both space and time. Experimentally, it can be accessed most directly by inelastic neutron scattering or X-ray Raman scattering.

The dynamic structure factor is most often denoted ${\displaystyle S({\vec {k}},\omega )}$, where ${\displaystyle {\vec {k}}}$ (sometimes ${\displaystyle {\vec {q}}}$) is a wave vector (or wave number for isotropic materials), and ${\displaystyle \omega }$ a frequency (sometimes stated as energy, ${\displaystyle \hbar \omega }$). It is defined as:

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