Intrinsic defect properties in GaN calculated byab initioand empirical potential methods

2004 ◽  
Vol 70 (24) ◽  
Author(s):  
Fei Gao ◽  
Eric J. Bylaska ◽  
William J. Weber
Keyword(s):  
Intrinsic Defect ◽  
Empirical Potential ◽  
Potential Methods

Semi-Empirical Potential Methods for Atomistic Simulations of Metals and Their Construction Procedures

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Seong-Gon Kim ◽  
M. F. Horstemeyer ◽  
M. I. Baskes ◽  
Masoud Rais-Rohani ◽  
Sungho Kim ◽  
...  
Keyword(s):  
Material Properties ◽  
Density Functional ◽  
Embedded Atom Method ◽  
Functional Theory ◽  
Empirical Potential ◽  
Embedded Atom ◽  
Target Values ◽  
Potential Methods ◽  
Semi Empirical ◽  
Cohesive Energies

General theory of semi-empirical potential methods including embedded-atom method and modified-embedded-atom method (MEAM) is reviewed. The procedures to construct these potentials are also reviewed. A multi-objective optimization (MOO) procedure has been developed to construct MEAM potentials with minimal manual fitting. This procedure has been applied successfully to develop a new MEAM potential for magnesium. The MOO procedure is designed to optimally reproduce multiple target values that consist of important material properties obtained from experiments and first-principle calculations based on density-functional theory. The optimized target quantities include elastic constants, cohesive energies, surface energies, vacancy-formation energies, and the forces on atoms in a variety of structures. The accuracy of the present potential is assessed by computing several material properties of Mg including their thermal properties. We found that the new MEAM potential shows a significant improvement over previously published potentials, especially for the atomic forces and melting temperature calculations.

Theoretical study of annulenes structure [14], [16] and [18] annulenes

1982 ◽  
Vol 47 (6) ◽  
pp. 1705-1720 ◽  
Author(s):  
Dušan Loos ◽  
Jaroslav Leška
Keyword(s):  
Theoretical Study ◽  
Enthalpies Of Formation ◽  
Equilibrium Geometry ◽  
Chemical Methods ◽  
Empirical Potential ◽  
Empirical Potentials ◽  
Quantum Chemical Methods ◽  
Degree Of Aromaticity ◽  
Bond Strengths ◽  
Potential Methods

The quantum-chemical methods EHT, CNDO/2, MINDO/2 and the method of empirical potentials have been used for calculation of equilibrium geometry of six isomers of [14] annulene, four isomers of [16], and three isomers of [18] annulenes. The bond strengths and degree of delocalization are characterized by the overlap populations and the Wiberg indices. Relative stabilities have been determined by comparison of enthalpies of formation calculated by the MINDO/2 and empirical potential methods. Influence of internal strain of the molecules on their stability lowering is discussed. The degree of aromaticity has been determined by calculation of several aromaticity indexes.

Reliability of Various Empirical Potential Methods

1980 ◽  
Vol 97 (1) ◽  
pp. 101-104 ◽  
Author(s):  
D. M. Esterling ◽  
A. Swaroop
Keyword(s):  
Empirical Potential ◽  
Potential Methods

Efficient AB Initio Tight Binding

1997 ◽  
Vol 491 ◽  
Author(s):  
Andrew Horsfield ◽  
Steven David Kenny
Keyword(s):  
Ab Initio ◽  
Tight Binding ◽  
Middle Ground ◽  
Numerical Techniques ◽  
Empirical Potential ◽  
Self Consistent ◽  
Recent Developments ◽  
Potential Methods ◽  
Ground Method

ABSTRACTTight binding is often seen as a middle ground method, lying between accurate ab iniiio methods, and fast empirical potential methods. The challenge is to make tight binding both as fast and as accurate as possible. One way to achieve this is to take established ab initio methods, and apply systematic approximations and efficient numerical techniques to obtain the greatest possible speed. A recently developed method, employing this approach, is described results presented for silicon, and recent developments (including fully self-consistent extensions) are reported.

Investigations on potential methods for the long-term monitoring of the state of fuel elements in dry storage casks

Kerntechnik ◽  
2018 ◽  
Vol 83 (6) ◽  
pp. 513-522 ◽  
Author(s):  
U. Hampel ◽  
A. Kratzsch ◽  
R. Rachamin ◽  
M. Wagner ◽  
S. Schmidt ◽  
...  
Keyword(s):  
The State ◽  
Dry Storage ◽  
Long Term Monitoring ◽  
Potential Methods ◽  
Fuel Elements ◽  
Term Monitoring

The empirical conformational surface of the co(ethylenediamine) ring

1990 ◽  
Vol 55 (6) ◽  
pp. 1427-1434 ◽  
Author(s):  
František Pavelčík ◽  
Eva Luptáková
Keyword(s):  
Potential Surface ◽  
Chelate Ring ◽  
Statistical Treatment ◽  
Mirror Image ◽  
Fold Axis ◽  
Empirical Potential ◽  
Reduction Of Dimensionality ◽  
Envelope Conformation ◽  
Structural Correlation ◽  
Structural Database

The conformational surface of the Co(en) chelate ring was studied by the method of structural correlation. The reduction of dimensionality of the conformation problem was achieved by employing the pseudorotation concept. The empirical potential surface was obtained by statistical treatment of 743 independent conformations from the Cambridge Structural Database. The theoretical potential surface was obtained by molecular mechanics. The minimal-energy conformation is gauche with the Co atom on the two-fold axis. Conformational flexibility also includes an envelope conformation with the N atom bent out of the plane. The transition between the mirror-image symmetrical conformations can occur by a pseudorotation pathway and is accompanied by increased planarity of the ring. The transition state is an envelope conformation with an out-plane Co atom.

scholarly journals Correction: Intrinsic defect formation and the effect of transition metal doping on transport properties in a ductile thermoelectric material α-Ag2S: a first-principles study

2021 ◽  
Author(s):  
Ho Ngoc Nam ◽  
Ryo Yamada ◽  
Haruki Okumura ◽  
Tien Quang Nguyen ◽  
Katsuhiro Suzuki ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transport Properties ◽  
Thermoelectric Material ◽  
First Principles ◽  
Defect Formation ◽  
Chem Phys ◽  
Intrinsic Defect ◽  
Transition Metal Doping ◽  
Metal Doping ◽  
First Principles Study

Correction for ‘Intrinsic defect formation and the effect of transition metal doping on transport properties in a ductile thermoelectric material α-Ag2S: a first-principles study’ by Ho Ngoc Nam et al., Phys. Chem. Chem. Phys., 2021, DOI: 10.1039/d0cp06624a.

scholarly journals Designing of Green Plasticizers and Assessment of the Effectiveness of Their Use

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1761
Author(s):  
Aliya K. Mazitova ◽  
Guliya K. Aminova ◽  
Irina N. Vikhareva
Keyword(s):  
Adipic Acid ◽  
Polymer Materials ◽  
Operational Parameters ◽  
Solid Domestic Waste ◽  
Polymer Waste ◽  
Synthetic Materials ◽  
Environmental Requirements ◽  
Potential Methods ◽  
High Set ◽  
Acid Esters

The growing anthropogenic load on the lithosphere is currently characterized by the alienation of huge areas for solid domestic waste. One of the most common pollutants is traditional plastics with a degradation period of over 100 years. In connection with the increasing environmental requirements, polymer materials, along with a high set of technological and operational parameters, must be environmentally friendly and biodegradable. The development of polymer composite materials that undergo accelerated physicochemical and biological changes in the natural environment due to the introduction of biodegradable additives is one of the potential methods for processing synthetic materials and ensures the release of significant areas of fertile soils and lands from the steadily increasing amount of polymer waste. The use of adipic acid esters as PVC plasticizers contributes to the production of biodegradable composites. The article describes a method for obtaining new esters of adipic acid, presents the results of studying their properties for practical use in PVC composites, and assesses the economic efficiency of preventing damage to the environment when using them.

Examining sharp restart in a Monte Carlo method for the linearized Poisson–Boltzmann equation

2020 ◽  
Vol 26 (3) ◽  
pp. 223-244
Author(s):  
W. John Thrasher ◽  
Michael Mascagni
Keyword(s):  
Monte Carlo ◽  
Free Energy ◽  
Monte Carlo Algorithm ◽  
Significant Bias ◽  
Poisson Boltzmann ◽  
Electrostatic Free Energy ◽  
Poisson Boltzmann Equation ◽  
The Stability ◽  
Potential Methods ◽  
The Individual

AbstractIt has been shown that when using a Monte Carlo algorithm to estimate the electrostatic free energy of a biomolecule in a solution, individual random walks can become entrapped in the geometry. We examine a proposed solution, using a sharp restart during the Walk-on-Subdomains step, in more detail. We show that the point at which this solution introduces significant bias is related to properties intrinsic to the molecule being examined. We also examine two potential methods of generating a sharp restart point and show that they both cause no significant bias in the examined molecules and increase the stability of the run times of the individual walks.

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