Comment on ``Local dimer-adatom stacking fault structures from 3x3 to 13x13 along Si(111)-7x7 domain boundaries''

Zhao et al. [Phys.Rev.B 58, 13824 (1998)] depicted several atomic structures of domain boundaries on a Si(111) surface and criticized the article by the present author and the co-workers. I will point out that their criticism is incorrect and their structure models have no consistency.Comment: 2 pages. Physical Review B, to appea

The Effect of Compressive and Tensile Strains on the Electron Structure of Phosphorene

A new promising semiconductor material (phosphorene) is studied using theoretical simulation. The possibilities of changing the magnitude and nature of interband transitions under the action of compressive and tensile stresses on the phosphorene crystal lattice are determined. It is found that phosphorene can be both direct-gap and indirect-gap semiconductors, depending on the magnitude and direction of stress action. Phosphorene can be used in new generation nanoelectronic devices with controlled movement of charge carriers

Влияние сжимающих и растягивающих напряжений на электронную структуру фосфорена

С помощью методов теоретического моделирования проведено исследование нового перспективного полупроводникового материала – фосфорена – и определены возможности изменения величины и характераего межзонных переходов при воздействии на кристаллическую решетку этого материала сжимающих и растягивающих напряжений. Установлено, что в зависимости от величины и направления воздействия напряжений материал может быть как прямозонным, так и непрямозонным полупроводником. Показана возможность применения фосфорена в наноэлектронных приборах нового поколения с управляемым направлением движения носителей заряда

Timesaving Double-Grid Method for Real-Space Electronic-Structure Calculations

We present a simple and efficient technique in ab initio electronic-structure calculation utilizing real-space double-grid with a high density of grid points in the vicinity of nuclei. This technique promises to greatly reduce the overhead for performing the integrals that involves non-local parts of pseudopotentials, with keeping a high degree of accuracy. Our procedure gives rise to no Pulay forces, unlike other real-space methods using adaptive coordinates. Moreover, we demonstrate the potential power of the method by calculating several properties of atoms and molecules.Comment: 4 pages, 5 figure

Monte Carlo study of Si(111) homoepitaxy

An attempt is made to simulate the homoepitaxial growth of a Si(111) surface by the kinetic Monte Carlo method in which the standard Solid-on-Solid model and the planar model of the (7x7) surface reconstruction are used in combination. By taking account of surface reconstructions as well as atomic deposition and migrations, it is shown that the effect of a coorparative stacking transformation is necessary for a layer growth.Comment: 4 pages, 5 figures. For Fig.1 of this article, please see Fig.2 of Phys.Rev. B56, 3583 (1997). To appear in Phys.Rev.B. (June 1998

First principles simulations of liquid Fe-S under Earth's core conditions

First principles electronic structure calculations, based upon density functional theory within the generalized gradient approximation and ultra-soft Vanderbilt pseudopotentials, have been used to simulate a liquid alloy of iron and sulfur at Earth's core conditions. We have used a sulfur concentration of $\approx 12$wt, in line with the maximum recent estimates of the sulfur abundance in the Earth's outer core. The analysis of the structural, dynamical and electronic structure properties has been used to report on the effect of the sulfur impurities on the behavior of the liquid. Although pure sulfur is known to form chains in the liquid phase, we have not found any tendency towards polymerization in our liquid simulation. Rather, a net S-S repulsion is evident, and we propose an explanation for this effect in terms of the electronic structure. The inspection of the dynamical properties of the system suggests that the sulfur impurities have a negligible effect on the viscosity of Earth's liquid core.Comment: 24 pages (including 8 figures

Phonons and related properties of extended systems from density-functional perturbation theory

This article reviews the current status of lattice-dynamical calculations in crystals, using density-functional perturbation theory, with emphasis on the plane-wave pseudo-potential method. Several specialized topics are treated, including the implementation for metals, the calculation of the response to macroscopic electric fields and their relevance to long wave-length vibrations in polar materials, the response to strain deformations, and higher-order responses. The success of this methodology is demonstrated with a number of applications existing in the literature.Comment: 52 pages, 14 figures, submitted to Review of Modern Physic