Low-temperature orientational order and possible domain structures in C(_{60}) fullerite
Abstract
Based on a simple model for ordering of hexagons on square planar lattice, an attempt has been made to consider possible structure of C(_{60}) fullerite in its low temperature phase. It is shown that hexagons, imitating fullerens oriented along (C_{3}) axes of \emph{sc} lattice, can be ordered into an ideal structure with four non-equivalent molecules in unit cell. Then the energy degeneracy for each hexagon rotations by (\pi /3) around its (C_{3}) axis leaves the translational and orientational order in this structure, but leads to a random distribution of (\pi /3) rotations and hence to {}``averaged{}'' unit cell with two molecules. However the most relevant structural defects are not these intrinsic \char`\"{}misorientations\char`\"{} but certain walls between the domains with different sequencies of the above-mentioned two (non-ideal) sublattices. Numeric estimates have been made for the anisotropic inter-molecular potential showing that the anisotropy is noticeably smaller for molecules in walls than in domains.
Cite
@article{arxiv.cond-mat/0012231,
title = {Low-temperature orientational order and possible domain structures in C(_{60}) fullerite},
author = {Vadim M. Loktev and Yuri G. Pogorelov and Julia N. Khalak},
journal= {arXiv preprint arXiv:cond-mat/0012231},
year = {2009}
}