Tuesday, May 21, 2013

1305.4257 (Yuri Martinez-Raton et al.)

Dimensional cross-over of hard parallel cylinders confined on
cylindrical surfaces

Yuri Martinez-Raton, Enrique Velasco
We derive, from the dimensional cross-over criterion, a fundamental-measure density functional for parallel hard curved rectangles moving on a cylindrical surface. We derive it from the density functional of circular arcs of length $\sigma$ with centers of mass located on an external circumference of radius $R_0$. The latter functional in turns is obtained from the corresponding 2D functional for a fluid of hard discs of radius $R$ on a flat surface with centers of mass confined onto a circumference of radius $R_0$. Thus the curved length of closest approach between two centers of mass of hard discs on this circumference is $\sigma=2R_0\sin^{-1}(R/R_0)$, the length of the circular arcs. From the density functional of circular arcs, and by applying a dimensional expansion procedure to the spatial dimension orthogonal to the plane of the circumference, we finally obtain the density functional of curved rectangles of edge-lengths $\sigma$ and $L$. The DF for curved rectangles can also be obtained by fixing the centers of mass of parallel hard cylinders of radius $R$ and length $L$ on a cylindrical surface of radius $R_0$. The phase behavior of a fluid of aligned curved rectangles is obtained by calculating the free-energy branches of smectic, columnar and crystalline phases for different values of the ratio $R_0/R$ in the range $1View original: http://arxiv.org/abs/1305.4257

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