We investigate the anomalous dynamics in smectic phases of short host rods where, counter-intuitively, long guest rod-shaped particles diffuse faster than the short host ones due to their precise size mismatch. In addition to the previously reported mean-square displacement, we analyze the time evolution of the self-Van Hove functions G(r, t), as this probability density function uncovers intrinsic heterogeneous dynamics. Through this analysis, we show that the dynamics of the host particles parallel to the director becomes non-Gaussian and therefore heterogeneous after the nematic-to-smectic-A phase transition, even though it exhibits a nearly diffusive behavior according to its mean-squared displacement. In contrast, the non-commensurate guest particles display Gaussian dynamics of the parallel motion, up to the transition to the smectic-B phase. Thus, we show that the self-Van Hove function is a very sensitive probe to account for the instantaneous and heterogeneous dynamics of our system and should be more widely considered as a quantitative and complementary approach of the classical mean-squared displacement characterization in diffusion processes.
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When bigger is faster: A self-Van Hove analysis of the enhanced self-diffusion of non-commensurate guest particles in smectics
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28 May 2021
Research Article|
May 24 2021
When bigger is faster: A self-Van Hove analysis of the enhanced self-diffusion of non-commensurate guest particles in smectics

M. Paul Lettinga
;
M. Paul Lettinga
a)
1
IBI-4, Forschungszentrum Jülich
, D-52425 Jülich, Germany
2
Laboratory for Soft Matter and Biophysics, KU Leuven
, Celestijnenlaan 200D, B-3001 Leuven, Belgium
a)Authors to whom correspondence should be addressed: p.lettinga@fz-juelich.de and eric.grelet@crpp.cnrs.fr
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Laura Alvarez
;
Laura Alvarez
2
Laboratory for Soft Matter and Biophysics, KU Leuven
, Celestijnenlaan 200D, B-3001 Leuven, Belgium
3
Centre de Recherche Paul-Pascal, CNRS and Université de Bordeaux
, 115 Avenue Schweitzer, F-33600 Pessac, France
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Olivera Korculanin;
Olivera Korculanin
1
IBI-4, Forschungszentrum Jülich
, D-52425 Jülich, Germany
2
Laboratory for Soft Matter and Biophysics, KU Leuven
, Celestijnenlaan 200D, B-3001 Leuven, Belgium
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Eric Grelet
Eric Grelet
a)
3
Centre de Recherche Paul-Pascal, CNRS and Université de Bordeaux
, 115 Avenue Schweitzer, F-33600 Pessac, France
a)Authors to whom correspondence should be addressed: p.lettinga@fz-juelich.de and eric.grelet@crpp.cnrs.fr
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a)Authors to whom correspondence should be addressed: p.lettinga@fz-juelich.de and eric.grelet@crpp.cnrs.fr
J. Chem. Phys. 154, 204901 (2021)
Article history
Received:
March 01 2021
Accepted:
April 07 2021
Connected Content
A companion article has been published:
Larger particles can diffuse faster than smaller ones
See also
Citation
M. Paul Lettinga, Laura Alvarez, Olivera Korculanin, Eric Grelet; When bigger is faster: A self-Van Hove analysis of the enhanced self-diffusion of non-commensurate guest particles in smectics. J. Chem. Phys. 28 May 2021; 154 (20): 204901. https://doi.org/10.1063/5.0049093
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