The intermediate scattering function for quasi-elastic scattering in the presence of memory friction
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Publication Date
2018Journal Title
Journal of Physics Communications
ISSN
2399-6528
Publisher
IOP Publishing
Volume
2
Issue
7
Type
Article
Metadata
Show full item recordCitation
Townsend, P., & Ward, D. (2018). The intermediate scattering function for quasi-elastic scattering in the presence of memory friction. Journal of Physics Communications, 2 (7) https://doi.org/10.1088/2399-6528/aad221
Abstract
We derive an analytical expression for the intermediate scattering function
of a particle on a flat surface obeying the Generalised Langevin Equation, with
exponential memory friction. Numerical simulations based on an extended phase
space method confirm the analytical results. The simulated trajectories provide
qualitative insight into the effect that introducing a finite memory timescale
has on the analytical line shapes. The relative amplitude of the long-time
exponential tail of the line shape is suppressed, but its decay rate is
unchanged, reflecting the fact that the cutoff frequency of the exponential
kernel affects short-time correlations but not the diffusion coefficient which
is defined in terms of a long-time limit. The exponential sensitivity of the
relative amplitudes to the decay time of the chosen memory kernel is a very
strong indicator for the prospect of inferring a friction kernel and the
physical insights from experimentally measured intermediate scattering
functions.
Keywords
Generalised Langevin equation, intermediate scattering function, surface diffusion
Sponsorship
EPSRC (1363145)
Identifiers
External DOI: https://doi.org/10.1088/2399-6528/aad221
This record's URL: https://www.repository.cam.ac.uk/handle/1810/279606
Rights
Licence:
http://creativecommons.org/licenses/by/4.0/
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