Green's functions are fundamental quantities that determine the linear responses of physical systems. The recent developments non-Hermitian systems, therefore, call for function formulas bands. This task is complicated by high sensitivity energy spectrums to boundary conditions, which invalidates straightforward generalization Hermitian formulas. Here, based on non-Bloch band theory, we obtain ...

Substitutional cobalt in ZnO has a weak preference for antiferromagnetic ordering. Stabilization of ferromagnetism is achieved through n-type doping, which can be understood through a band coupling model. However, the description of the transition to a ferromagnetic ground state varies within different levels of band theory; issues arise due to the density functional theory underestimation of t...

A first principles quasiparticle theory for band offsets of heterojunctious is developed and used to compute the vaJence band offset AE. for the prototypical AIAs-GIAs(001) interface. The result AE . = 0.53-1-0.05 eV is in good qreement with recent experimental values and in particular with the m ~ t recent photolumine~ence dst~ AE. ffi 0.56 ± 0.03 eV for an MBE grown sample. We show that there...

Ladder-type polymers, obtained by small modifications of the atomic structure of ladder-type polythiophene, are studied using density-functional theory calculations. Within the local-density and GW approximations, it is found that upon a simple substitution of the sulfur atoms by nitrogen and boron atoms, the band structure of the resulting polymer exhibits band overlap between the occupied and...

A theory is developed for calculating vertical tunneling current between two sheets of bilayer graphene separated by a thin, insulating layer of hexagonal boron nitride, neglecting many-body effects. Results are presented using physical parameters that enable comparison of the theory with recently reported experimental results. Observed resonant tunneling and negative differential resistance in...

We develop a theory for the electron-phonon interaction effects on the electronic properties of graphene. We analytically calculate the electron self-energy, spectral function, and the band velocity renormalization due to phonon-mediated electron-electron interaction, finding that phonon-mediated electron-electron coupling has a large effect on the graphene band structure renormalization. Our a...

The electronic band gaps measured in fluorescence spectroscopy on individual single wall carbon nanotubes isolated within micelles show significant deviations from the predictions of one electron band theory. We resolve this problem by developing a theory of the electron-hole interaction in the photoexcited states. The one-dimensional character and tubular structure introduce a novel relaxation...

A concept of the sub-band operator of multi-band wavelets is introduced, the theory of d-circular matrices is developed and the upper bound and the lower bound of the norm of the sub-band operator are obtained. Examples are provided to illustrate the results proposed in this paper.