Low Temperature Physics: 29, 429 (2003); https://doi.org/10.1063/1.1542507 (11 pages)
Физика Низких Температур: Том 29, Выпуск 5 (Май 2003), c. 577-589 ( к оглавлению , назад )
On the orientational relief of the intermolecular potential and the structure of domain walls in fullerite C60
Julia M. Khalack1,2 and Vadim M. Loktev1
1Bogolyubov Institute for Theoretical Physics of the NAS of Ukraine 14b Metrologichna Str., Kyiv-143, 03143 Ukraine
Received November 29, 2002
A simple planar model for an orientational ordering of threefold molecules on a triangular lattice modeling a close-packed (111) plane of fullerite is considered. The system has 3-sublattice ordered ground state which includes 3 different molecular orientations. There exist 6 kinds of
orientational domains, which are related with a permutation or a mirror symmetry. Interdomain walls are found to be rather narrow. The model molecules have two-well orientational potential profiles, which are slightly effected by a presence of a straight domain wall. The reason is a stronger correlation between neighbor molecules in the triangular lattice versus the square lattice previously considered. A considerable reduction (up to one order) of the orientational interwell potential barrier is found in the core regions of essentially two-dimentional potential defects, such as a three-domain boundary or a kink in the domain wall. For ultimately uncorrelated nearest neighbors the height of the interwell barrier can be reduced even by a factor of 102.