Peculiar Doping Behavior of Si:Be.

ABSTRACTThe total energies and structures of a number of Be-induced defects in Si are investigated using ab-initio local density calculations. Our primary results are: 1) The geometry of the isoelectronic center is found to correspond to a [111] substitutionalinterstitial pair (SIP); 2) The low energy defect spectrum includes large Be complexes containing at least one substitutional atom; and 3) Simple bonding rules exist for the stability of the different types of bonds in the material. Thus the Si-Be bond is found to be stable for all defect configurations while the Be-Be bond is metastable.

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Electronic Structure of Li-Impurities in ZnSe.

MRS Proceedings ◽

10.1557/proc-163-81 ◽

1989 ◽

Vol 163 ◽

Author(s):

T. Oguchi ◽

T. Sasaki ◽

H. Katayama-Yoshida

Keyword(s):

Electronic Structures ◽

Density Functional ◽

Local Density ◽

Lattice Relaxation ◽

Interstitial Site ◽

Functional Approach ◽

Tetrahedral Interstitial Site ◽

Total Energies ◽

The Stability ◽

Impurity Sites

AbstractElectronic properties of ZnSe with a Li impurity are investigated with use of the local-density-functional approach. The electronic structures are calculated for different impurity sites by taking the neighboring lattice relaxation into account. By comparing their total energies, the stability of the Li impurity in ZnSe is discussed. It is proposed that the Li impurity at the substitutional Zn site might be unstable to the tetrahedral interstitial site with an ionization of Li and a vacancy at the Zn site.

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Pseudoatomic Orbital Compact Basis Sets: Applications to Metallic Systems

MRS Proceedings ◽

10.1557/proc-141-13 ◽

1988 ◽

Vol 141 ◽

Author(s):

Robert W. Jansen ◽

B. H. Klein

Keyword(s):

Free Electron ◽

Local Density Approximation ◽

Local Density ◽

Low Energy ◽

Basis Sets ◽

Density Approximation ◽

Self Consistent ◽

Total Energies ◽

Energy Convergence ◽

Metallic Systems

AbstractA self-consistent orbital-based scheme is applied to metallic systems and is found to be efficient for these materials. The technique uses the local density approximation in the pseudopotential framework, but replaces the planewave basis by a basis pseudoatomic orbitals constructed directly from the pseudoatoms. Free electron-like wavefunction components are handled by orthogonalizing the orbital basis to a few low energy planewaves as needed for good eigenvalue and total energy convergence. The method is fast and versatile enough to be used for a variety of problems. Applications to bulk bandstructures, total energies, and forces in Al and Nb are presented.

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Ab initio band theory approach to electron energy loss near edge structures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104595 ◽

1988 ◽

Vol 46 ◽

pp. 506-507

Author(s):

Xudong Weng ◽

O.F. Sankey ◽

Peter Rez

Keyword(s):

Ab Initio ◽

Local Density ◽

Interpolation Method ◽

Atomic Orbital ◽

Plane Waves ◽

Large Set ◽

Theory Approach ◽

Band Theory ◽

Atomic Orbitals ◽

Pseudopotential Calculations

Single electron band structure techniques have been applied successfully to the interpretation of the near edge structures of metals and other materials. Among various band theories, the linear combination of atomic orbital (LCAO) method is especially simple and interpretable. The commonly used empirical LCAO method is mainly an interpolation method, where the energies and wave functions of atomic orbitals are adjusted in order to fit experimental or more accurately determined electron states. To achieve better accuracy, the size of calculation has to be expanded, for example, to include excited states and more-distant-neighboring atoms. This tends to sacrifice the simplicity and interpretability of the method.In this paper. we adopt an ab initio scheme which incorporates the conceptual advantage of the LCAO method with the accuracy of ab initio pseudopotential calculations. The so called pscudo-atomic-orbitals (PAO's), computed from a free atom within the local-density approximation and the pseudopotential approximation, are used as the basis of expansion, replacing the usually very large set of plane waves in the conventional pseudopotential method. These PAO's however, do not consist of a rigorously complete set of orthonormal states.

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Scalable Approach to High Coverages on Oxides via Iterative Training of a Machine-Learning Algorithm

10.26434/chemrxiv.10288514.v1 ◽

2019 ◽

Author(s):

Andrew Medford ◽

Shengchun Yang ◽

Fuzhu Liu

Keyword(s):

Machine Learning ◽

Chemical Potential ◽

Learning Algorithm ◽

Absolute Error ◽

Low Energy ◽

Training Data ◽

High Coverage ◽

Metal Compounds ◽

Adsorption Energies ◽

The Stability

Understanding the interaction of multiple types of adsorbate molecules on solid surfaces is crucial to establishing the stability of catalysts under various chemical environments. Computational studies on the high coverage and mixed coverages of reaction intermediates are still challenging, especially for transition-metal compounds. In this work, we present a framework to predict differential adsorption energies and identify low-energy structures under high- and mixed-adsorbate coverages on oxide materials. The approach uses Gaussian process machine-learning models with quantified uncertainty in conjunction with an iterative training algorithm to actively identify the training set. The framework is demonstrated for the mixed adsorption of CHx, NHx and OHx species on the oxygen vacancy and pristine rutile TiO2(110) surface sites. The results indicate that the proposed algorithm is highly efficient at identifying the most valuable training data, and is able to predict differential adsorption energies with a mean absolute error of ~0.3 eV based on <25% of the total DFT data. The algorithm is also used to identify 76% of the low-energy structures based on <30% of the total DFT data, enabling construction of surface phase diagrams that account for high and mixed coverage as a function of the chemical potential of C, H, O, and N. Furthermore, the computational scaling indicates the algorithm scales nearly linearly (N1.12) as the number of adsorbates increases. This framework can be directly extended to metals, metal oxides, and other materials, providing a practical route toward the investigation of the behavior of catalysts under high-coverage conditions.

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ASSESSMENT OF PINE CROPS GROWTH IN BAIMAK FORESTRY

RUSSIAN ELECTRONIC SCIENTIFIC JOURNAL ◽

10.31563/2308-9644-2020-37-3-83-90 ◽

2020 ◽

Vol 37 (3) ◽

pp. 83-90

Author(s):

T.Z. Mutallapov ◽

Keyword(s):

Scots Pine ◽

Forest Ecosystem ◽

Distribution Curve ◽

Comparative Assessment ◽

Tree Distribution ◽

Entire Structure ◽

Structure Changes ◽

Large Trees ◽

Different Types ◽

The Stability

The article presents the results of evaluating the growth of Scots pine in the Baymak forest area. The analysis of forestry and taxation indicators of Scots pine crops on the studied sample areas is carried out, and a comparative assessment of the growth of forest crops growing in different types of forest is given. Increased competition in plantings leads to the natural decline of stunted trees, which is the result of differentiation in the stand. As a result, its structure changes, the number of large trees increases, and, accordingly, the stability of the forest ecosystem increases. In this regard, the appearance of the tree distribution curve by thickness levels also changes. It becomes more "flat", and its competitive load is more evenly distributed over the entire structure of the stand, and competition is weakened.

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A Survey on Computational Methods for Essential Proteins and Genes Prediction

Current Bioinformatics ◽

10.2174/1574893613666181112150422 ◽

2019 ◽

Vol 14 (3) ◽

pp. 211-225 ◽

Cited By ~ 2

Author(s):

Ming Fang ◽

Xiujuan Lei ◽

Ling Guo

Keyword(s):

Computational Methods ◽

Drug Targets ◽

Disease Genes ◽

Essential Proteins ◽

Experimental Identification ◽

Cellular Life ◽

Different Types ◽

The Stability ◽

Human Disease Genes ◽

Biology Research

Background: Essential proteins play important roles in the survival or reproduction of an organism and support the stability of the system. Essential proteins are the minimum set of proteins absolutely required to maintain a living cell. The identification of essential proteins is a very important topic not only for a better comprehension of the minimal requirements for cellular life, but also for a more efficient discovery of the human disease genes and drug targets. Traditionally, as the experimental identification of essential proteins is complex, it usually requires great time and expense. With the cumulation of high-throughput experimental data, many computational methods that make useful complements to experimental methods have been proposed to identify essential proteins. In addition, the ability to rapidly and precisely identify essential proteins is of great significance for discovering disease genes and drug design, and has great potential for applications in basic and synthetic biology research. Objective: The aim of this paper is to provide a review on the identification of essential proteins and genes focusing on the current developments of different types of computational methods, point out some progress and limitations of existing methods, and the challenges and directions for further research are discussed.

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The effect of different types of lactose monohydrate on the stability of acetylcholinesterase immobilized on carriers designed to detect nerve agents

Journal of Chemical Technology & Biotechnology ◽

10.1002/jctb.6700 ◽

2021 ◽

Author(s):

Jiří Zeman ◽

Sylvie Pavloková ◽

David Vetchý ◽

Vladimír Pitschmann

Keyword(s):

Nerve Agents ◽

Lactose Monohydrate ◽

Different Types ◽

The Stability

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Stability of aerobic granular sludge under low energy consumption: Optimization of granular size distribution by a novel internal component

Environmental Science Water Research & Technology ◽

10.1039/d1ew00060h ◽

2021 ◽

Author(s):

Runjuan Cao ◽

Yatong Ji ◽

Taixing Han ◽

Jingsong Deng ◽

Liang Zhu ◽

...

Keyword(s):

Energy Consumption ◽

Granular Sludge ◽

Pollutant Removal ◽

Low Energy ◽

Aerobic Granular Sludge ◽

Mesh Screen ◽

Energy Consumption Optimization ◽

Low Energy Consumption ◽

Internal Component ◽

The Stability

To enhance the stability and pollutant removal performance of an aerobic granular sludge (AGS), four groups of AGS reactors with different pore sizes of mesh screen (R1 is control reactor,...

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