QUANTUM-CHEMICAL CALCULATION OF THE GRAPHENE OXIDE MOLECULE IN THE FRAMEWORK OF THE NAKAJIMA-MATSUO AND LERFA-KLINOVSKY

Using the classical semi-empirical quantum-chemical method МNDO, for the first time the calculation of graphene oxide molecules was performed within the framework of the Nakajima-Matsuo and Lerf-Klinovsky models. The acidic strength of these models and the Hartree energy are theoretically estimated. It was found that the studied graphene oxides belong to dielectrics and to the class of intermediate Bronsted acids (pKa = 9-14).

THE CAPACITANCE MODEL FOR PERSISTENT CURRENTS IN MESOSCOPIC METAL RINGS

We review recent theoretical work on persistent currents in mesoscopic normal-metal rings and present a detailed discussion the generalized capacitance model.20(a) This model provides a natural explanation for the surprisingly large experimentally observed currents in the diffusive regime. We pay particular attention to the problem of screening in a thin mesoscopic ring, and argue that screening corrections to the flux-dependent part of the Hartree energy are negligible provided the condition [Formula: see text] is satisfied. Here e2/C0 is the classical charging energy for adding one electron to the system, and [Formula: see text] is the average number of energy levels within an interval of width E c below the Fermi energy µ, where E c is the Thouless energy. This condition is equivalent with (k F l)(L⊥/L)2 ≪ 1 (where l is the elastic mean free path, L is the circumference and L⊥ is the transverse thickness of the ring), and shows that the ring geometry plays an important role. In thin rings the mesoscopic persistent current is universal in precisely the same sense as the variance of the conductance.