Thermodynamic properties of polyacenes

Carbon nanoribbons have been a subject of great interest lately because of their interesting physical properties, particularly their use as electrodes in lithium-based batteries, in a way to improve the performance of these batteries. By means of a diagrammatic perturbation expansion of the Hubbard model, the thermodynamic properties of a cyclical polyacene have been calculated. The entropy, magnetic susceptibility and specific heat curves present crossing points. The molecular hardness multiplied by the carbon number (NC) in a polyacene molecule is a relevant parameter to determine its energy storage capability. Our results show that this parameter versus NC, for some cyclical polyacenes, presents a peak in NC=36 and it practically does not change for NC>60. The behavior for NC<30 is very similar to that of the available experimental curve for polyacenes