Expansion Of Electron Wave Functions Research Articles

Computer simulation of edge-terminated carbon nanoribbons

In this paper, we present the results of ab initio simulation of edge-terminated carbon nanoribbons (CNRs). The calculations were performed using the electron density functional theory with the expansion of electron wave functions in plane waves in the Quantum Espresso software package [1]. The effect of various edge termination types on the band structure of graphene nanoribbons is studied. The data obtained showed that hydrogen and fluorine termination has a very weak effect on the structure. Sulfur or bromine termination causes a semiconductor-to-metal transition. The cause of the change in the conductivity type is the appearance of the electron dispersion curve crossing the nanoribbon band gap. At the same time, the dispersion dependences of the ribbon edge-terminated with alternating chlorine and hydrogen atoms do not exhibit such a change, and the curve mentioned above is not observed. The causes of the observed effects are analyzed.

Optical lineshapes and electronic eigenstates of substitutional defects and vacancies

A scattering-theoretical method for the study of the electronic structure of defects in crystalline solids is developed. The authors' formulation requires the expansion of electronic wavefunctions in a local basis consistent with the band structure of the solid. Appropriately chosen local orbitals are included, even for the analysis of a vacancy. To illustrate the method they perform an exact diagonalisation of the one-electron Hamiltonian for the coupling of four local impurity states to a single electronic band. Their analysis of optical properties includes a comparison with results on internal photoionisation of shallow and deep acceptor levels in silicon. A new simple expression yields excellent fits to the lineshapes of boron, aluminium, indium and zinc impurities. In all these cases inclusion of the p character of the valence bands and the complete treatment of the continuum scattering states is required.

Expansion of Electronic Wave Functions of Molecules in Terms of ``United-Atom'' Wave Functions

Expansion of Electronic Wave Functions of Molecules in Terms of ``United-Atom'' Wave Functions