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available distance (from the center of the cavity to its walls) for particles, is in the
triangular cavity.
4 Conclusions
In this work we have studied the behavior of confined particles (inside circular,
square and triangular cavities) interacting by means of three different potentials
namely, Lenard-Jones (CLJ), soft Lenard-Jones (SLJ) and hard Lenard-Jones (HLJ)
potentials. We showed that diffusion is strongly affected when particles are confined
inside nanometric cavities. In this work, we varied the number of particles inside the
cavity (density) while keeping a reduced temperature
T
∗
=
1, and studied particle
displacement by using Molecular dynamics simulations in a canonical ensemble. We
showed that for low densities (
ˁ
∗
=
1) diffusion for all fluids is similar, and that the
highest MSD occurs for a triangular cavity since the longest available distance (from
the center of the cavity to its boundaries) occurs in the triangular cavity. It is also found
that the highest MSD occurs for particles with attractive interactions (CLJ). The first
relevant result in this work occurs for moderated densities (
ˁ
∗
0
.
5). Here, HLJ
particles confined in a triangular cavity, strongly reduce their MSD due to the absence
of spatial order, resulting in a low particle speed. This effect should be investigated in
detail in a future work. We also observe that fluids with attractive interactions (CLJ)
and with week repulsion (SLJ) possess similar diffusivities inside all the cavities.
Finally, the second relevant result is obtained at high densities (
ˁ
∗
=
0
.
=
.
75) where
fluids with week repulsion (SLJ) and for all the cavity shapes, show the lowest MSD.
This is a surprising result that can be explained due to the appearance of spatial
order that particles show inside all the cavities. We conclude by pointing out that
the appearance of order in our system shows how the interplay of confinement and
interaction may produce non-trivial behavior in geometrically constrained fluids.
0
Acknowledgments
We thank CONACYT-Mexico (Project No. 178963) for Financial support.
Computational resources for this work were provided by the LSVP at UAM-I and also in part by
Xiuhcoatl-CINVESTAV.
References
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