Ab initio cluster calculations of defects in solids

1992 ◽  
Vol 341 (1661) ◽  
pp. 351-360 ◽  
Keyword(s):  
Density Functional ◽  
Local Density ◽  
Rapid Determination ◽  
Molecular Solids ◽  
Unusual Structure ◽  
Bonded Materials ◽  
Ionic Systems ◽  
Covalently Bonded ◽  
Local Density Functional Theory

A method based on local density functional theory is described which leads to the rapid determination of the structure, vibrational and electronic properties of clusters as large as 100-150 atoms. The technique is particularly suitable for molecular solids, covalently bonded materials where the clusters are terminated by hydrogen, and to ionic systems where the termination consists of a set of distributed charges. The strengths and weaknesses of the method are detailed together with an application to the interstitial carbon-oxygen complex in silicon where oxygen is found to be over-coordinated. The good agreement obtained for the vibrational modes of the complex lends support to the unusual structure found.

ALL-ELECTRON LOCAL-DENSITY DETERMINATION OF THE ELECTRONIC STRUCTURE AND SURFACE ENERGY OF ZR(0001)

1993 ◽  
Vol 07 (01n03) ◽  
pp. 520-523
Author(s):  
J. I. LEE ◽  
S. K. HWANG ◽  
S. C. HONG ◽  
A. J. FREEMAN
Keyword(s):  
Electronic Structure ◽  
Surface Energy ◽  
Density Functional ◽  
Local Density ◽  
Full Potential ◽  
Functional Theory ◽  
Plane Wave Method ◽  
Local Density Functional Theory ◽  
Linearized Augmented Plane Wave

The electronic structure and surface energy of Zr(0001) is determined theoretically using the all-electron full-potential linearized augmented plane wave method based on local-density functional theory. We found the value of surface energy to be 1.6 J/m 2 which is comparable to the value estimated from experiments on liquid zirconium at the melting point. It is, however, much smaller than the surface energies of W(001), V(001) and bcc Co(001). The calculated valence charge density, workfunction, and layer projected density of states for Zr(0001) are also presented.

Structure and Stability of Grain Boundaries in Molybdenum with Segregated Carbon Impurities

1999 ◽  
Vol 578 ◽  
Author(s):  
R. Janisch ◽  
T. Ochs ◽  
A. Merkle ◽  
C. Elsässer
Keyword(s):  
Ab Initio ◽  
Grain Boundaries ◽  
Density Functional ◽  
Local Density ◽  
Structural Parameters ◽  
Carbide Phases ◽  
Carbon Impurities ◽  
Transmission Electron ◽  
Local Density Functional Theory ◽  
Symmetrical Tilt

AbstractThe segregation of interstitial impurities to symmetrical tilt grain boundaries (STGB) in bodycentered cubic transition metals is studied by means of ab-initio electronic-structure calculations based on the local density functional theory (LDFT). Segregation energies as well as changes in atomic and electronic structures at the ΣE5 (310) [001] STGB in Mo caused by segregated interstitial C atoms are investigated. The results are compared to LDFT data obtained previously for the pure Σ5 (310) [001] STGB in Mo. Energetic stabilities and structural parameters calculated ab initio for several crystalline Molybdenum Carbide phases with cubic, tetragonal or hexagonal symmetries and different compositions, MoCx, are reported and compared to recent high-resolution transmission electron microscopy (HRTEM) observations of MoCx, intergranular films and precipitates formed by C segregation to a Σ5 (310) [001] STGB in a Mo bicrystal.

scholarly journals Structure and Electrochemical Potential Simulation for the Cathode Material Li1+xV3O8

1997 ◽  
Vol 496 ◽  
Author(s):  
R. Benedek ◽  
M. M. Thackeray ◽  
L. H. Yang
Keyword(s):  
Density Functional ◽  
Structural Information ◽  
Local Density ◽  
Tetrahedral Site ◽  
Low Energy ◽  
Electrochemical Potential ◽  
X Ray Diffraction ◽  
X Ray ◽  
Local Density Functional Theory ◽  
Two Phases

ABSTRACTThe structure and electrochemical potential of monoclinic Li1+xV3O8 were calculated within the local-density-functional-theory framework by use of plane-wave-pseudopotential methods. Special attention was given to the compositions 1+x=1.2 and 1+x=4, for which x-ray diffraction structure refinements are available. The calculated low-energy configuration for 1+x=4 is consistent with the three Li sites identified in x-ray diffraction measurements and predicts the position of the unobserved Li. The location of the tetrahedrally coordinated Li in the calculated low-energy configuration for 1+x=1.5 is consistent with the structure measured by x-ray diffraction for Li1.2V3O8. Calculations were also performed for the two monoclinic phases at intermediate Li compositions, for which no structural information is available. Calculations at these compositions are based on hypothetical Li configurations suggested by the ordering of vacancy energies for Li4V3O8 and tetrahedral site energies in Li1.5V3O8. The internal energy curves for the two phases- cross near 1+x=3. Predicted electrochemical potential curves agree well with experiment.

Some applications of local density functional theory to the calculation of reaction energetics

1993 ◽  
Vol 85 (1-3) ◽  
pp. 127-136 ◽  
Author(s):  
Peter Politzer ◽  
Jorge M. Seminario ◽  
Monica C. Concha ◽  
Jane S. Murray
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Local Density ◽  
Functional Theory ◽  
Local Density Functional Theory ◽  
Local Density Functional

scholarly journals Effect of Hartree–Fock pseudopotentials on local density functional theory calculations

2018 ◽  
Vol 20 (27) ◽  
pp. 18844-18849 ◽  
Author(s):  
Hengxin Tan ◽  
Yuanchang Li ◽  
S. B. Zhang ◽  
Wenhui Duan
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Density Functional ◽  
Local Density ◽  
Density Functional Theory Calculations ◽  
Optimal Choice ◽  
Functional Theory ◽  
Hartree Fock ◽  
Local Density Functional Theory ◽  
Local Density Functional

Optimal choice of the element-specific pseudopotential improves the band gap.

Laplacian free and asymptotic corrected semilocal exchange potential applied to the band gap of solids

2019 ◽  
Vol 21 (35) ◽  
pp. 19639-19650 ◽  
Author(s):  
Abhilash Patra ◽  
Subrata Jana ◽  
Hemanadhan Myneni ◽  
Prasanjit Samal
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Density Functional ◽  
Local Density ◽  
Exchange Potential ◽  
Functional Theory ◽  
Type Semiconductor ◽  
Local Density Functional Theory ◽  
Local Density Functional

Improved band gap of n-type semiconductor ZrS2 within semi-local density functional theory is shown. The band gap of mBR-TBMBJ agrees well with the hybrid HSE06 functional.

scholarly journals First-Principles Determination of the Polarizabilities of Carbon Tubules as a Function of Length

1994 ◽  
Vol 349 ◽  
Author(s):  
Andrew A. Quong ◽  
Mark R. Pederson
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Valence Electron ◽  
Local Density ◽  
Density Approximation ◽  
Functional Theory ◽  
Size Dependent ◽  
The Density Functional Theory ◽  
Linear And Nonlinear

ABSTRACTWe use the local-density-approximation to the density-functional theory to determine the axial polarizabilities of fullerene tubules as a function of length and winding topologies. Specifically, we present linear polarizabilities for tubules of composition C12H24, C36H24, C40H20 and C60H24. The size-dependent variation in the dipole-coupled gaps between pairs of occupied and unoccupied levels leads to enhancements in the polarizability per valence electron as the length of the tubule increases. The results are compared to recent densityfunctional based calculations of the linear and nonlinear polarizabilities for fullerene and benzene molecules.

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