Rotational oscillations of a molecular chain with quadrupolar interaction

摘要

Molecular chains with rotational degree of freedom in the plane of an adsorbing surface and quadrupolar interaction between linear molecules are investigated theoretically. It is found that alternation ordering of the molecules is preferable. Equations of rotational movement are derived and solved for linear oscillations. It is shown that dispersion relation has two optic branches of rotational excitations. The normal coordinates are found to be strongly dependent on dispersion. In the long wave limit normal coordinates are symmetric and antisymmetric. The heat capacity of the molecular chain is found at low temperature.