xmlui.dri2xhtml.METS-1.0.item-contributor-funder:
Ministerio de Economía y Competitividad (España)
Sponsor:
Financial support under grant FIS2017-86007-C3-1-P from Ministerio de Economía, Industria y Competitividad (MINECO) of Spain, and PGC2018-096606-BI00 from Agencia Estatal de Investigación-Ministerio de Ciencia e Innovación of Spain, is acknowledged.
Project:
Gobierno de España. FIS2017-86007-C3-1-P Gobierno de España. PGC2018-096606-BI00
Keywords:
Density functional theory
,
Hard kites
,
Tetratic phase
,
Triatic phase
Using density-functional theory we theoretically study the orientational properties of uniform phases of hard
kites—two isosceles triangles joined by their common base. Two approximations are used: scaled particle theory
and a new approach that better approxUsing density-functional theory we theoretically study the orientational properties of uniform phases of hard
kites—two isosceles triangles joined by their common base. Two approximations are used: scaled particle theory
and a new approach that better approximates third virial coefficients of two-dimensional hard particles. By
varying some of their geometrical parameters, kites can be transformed into squares, rhombuses, triangles, and
also very elongated particles, even reaching the hard-needle limit. Thus, a fluid of hard kites, depending on
the particle shape, can stabilize isotropic, nematic, tetratic, and triatic phases. Different phase diagrams are
calculated, including those of rhombuses, and kites with two of their equal interior angles fixed to 90º, 60º, and 75º. Kites with one of their unequal angles fixed to 72º, which have been recently studied via Monte Carlo
simulations, are also considered. We find that rhombuses and kites with two equal right angles and not too large
anisometry stabilize the tetratic phase but the latter stabilize it to a much higher degree. By contrast, kites with
two equal interior angles fixed to 60º stabilize the triatic phase to some extent, although it is very sensitive to
changes in particle geometry. Kites with the two equal interior angles fixed to 75º have a phase diagram with
both tetratic and triatic phases, but we show the nonexistence of a particle shape for which both phases are stable
at different densities. Finally, the success of the new theory in the description of orientational order in kites is
shown by comparing with Monte Carlo simulations for the case where one of the unequal angles is fixed to 72º.
These particles also present a phase diagram with stable tetratic and triatic phases.[+][-]