Biintercalation and Electron Energy Spectrum in Layer Nanostructures

Effect of biintercalation on the behavior of electron energy spectra and thermodynamic characteristics of nanostructures related to biintercalate is studied. Electron energy spectrum of biintercalate was calculated within the framework of virtual crystal with different type of bounding within the sandwich of monolayers (tied by strong ion-covalent bounding) and the weak van der Waals one across the sandwiches by the method of two-time retarded Green's functions. The concentration of free carriers and change of free energy $\Delta \mathbf{F}$ at low temperatures depending on Fermi energy was calculated. It was shown that there is a certain interval of Fermi energy at which biintercalation leads to the non monotonic decrease of $\Delta \mathbf{F}$ with two minima. It was found that sign of $\Delta \mathbf{F}$ strongly depends on the intercalant nature. The greatest advantage occurred if the case of quite different intercalants was chosen.