scholarly journals Cohesive properties of group-III nitrides: A comparative study of all-electron and pseudopotential calculations using the generalized gradient approximation

2002 ◽  
Vol 65 (24) ◽  
Author(s):  
M. Fuchs ◽  
J. L. F. Da Silva ◽  
C. Stampfl ◽  
J. Neugebauer ◽  
M. Scheffler
Keyword(s):  
Comparative Study ◽  
Group Iii Nitrides ◽  
Generalized Gradient ◽  
Group Iii ◽  
Generalized Gradient Approximation ◽  
Cohesive Properties ◽  
Pseudopotential Calculations

ELASTIC AND ELECTRONIC PROPERTIES OF Hf2SnC AND Hf2SnN

2009 ◽  
Vol 23 (26) ◽  
pp. 5155-5161 ◽  
Author(s):  
A. ROUMILI ◽  
Y. MEDKOUR ◽  
D. MAOUCH
Keyword(s):  
Plane Wave ◽  
Density Distribution ◽  
Charge Density ◽  
Electronic Properties ◽  
Generalized Gradient ◽  
Charge Density Distribution ◽  
Generalized Gradient Approximation ◽  
Equilibrium Volume ◽  
Pseudopotential Calculations ◽  
Experimental Values

Using plane wave pseudopotential calculations and the generalized gradient approximation, we have studied the structural, elastic, and electronic properties of Hf 2 SnC and Hf 2 SnN . Lattice parameters and equilibrium volume are in satisfactory agreement with the experimental values. Electronic properties show a metallic character of both compounds. Bonds are originally made from hybridized Hf d– C p (or N p) states, and Hf d– Sn p states, confirmed by strong coupling between Hf–C (or N), and Hf–Sn bonding from the charge density distribution.

A comparative study of small 3d-metal oxide (FeO)n, (CoO)n, and (NiO)n clusters

2016 ◽  
Vol 18 (40) ◽  
pp. 27858-27867 ◽  
Author(s):  
G. L. Gutsev ◽  
K. G. Belay ◽  
K. V. Bozhenko ◽  
L. G. Gutsev ◽  
B. R. Ramachandran
Keyword(s):  
Density Functional Theory ◽  
Metal Oxide ◽  
Comparative Study ◽  
Electronic Structures ◽  
Density Functional ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Metal Oxide Clusters ◽  
Generalized Gradient Approximation

Geometrical and electronic structures of the 3d-metal oxide clusters (FeO)n, (CoO)n, and (NiO)n are computed using density functional theory with the generalized gradient approximation in the range of 1 ≤ n ≤ 10.

scholarly journals Estimation of Lattice Constants and Band Gaps of Group-III Nitrides using Local and Semi Local Functionals

2018 ◽  
Vol 34 (4) ◽  
pp. 2137-2143 ◽  
Author(s):  
Sandeep Arora ◽  
Dharamvir Singh Ahlawat ◽  
Dharambir Singh
Keyword(s):  
Band Gap ◽  
Local Density ◽  
Group Iii Nitrides ◽  
Lattice Parameters ◽  
Exchange Potential ◽  
Generalized Gradient ◽  
Group Iii ◽  
Lattice Constants ◽  
Mean Error ◽  
Gap Values

We performed the optimization of lattice constants of Group- III nitrides (InN, AlN, GaN) in wurtzite and Zinc blende structures using various semilocal exchange correlation functional in generalized gradient approximations (GGA) namely PBE, WC, PBEsol in addition to local density approximation (LDA) functional. We used these optimized lattice parameters to predict the band gap values using modified Becke Johnson exchange potential with original and improved parameterization as suggested by David Koller for semiconductors having band gap values below 7eV. Among the different functionals considered, PBEsol optimize the lattice parameters with smallest mean error (0.00639 Å) relative to experimental values, while WC approximation with a slightly greater value of mean error (0.00513 Å). It is shown that mBJLDA approximation improves the band gap for the materials studied when compared with LDA and GGA results. It is also shown that LDA optimized parameters with mBJLDA approximation, which leads to mean error of 0.162 eV reproduces the experimental band gap in most efficient way.

BULK MODULUS CALCULATIONS FOR GROUP-IV CARBIDES AND GROUP-III NITRIDES

2004 ◽  
Vol 18 (24) ◽  
pp. 1247-1254 ◽  
Author(s):  
A. MAHMOOD ◽  
L. E. SANSORES ◽  
J. HEIRAS
Keyword(s):  
Bulk Modulus ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Wide Band ◽  
Group Iii Nitrides ◽  
Group Iv ◽  
Hard Coatings ◽  
Generalized Gradient ◽  
Group Iii ◽  
Quantum Mechanical Method

Wide band gap semiconductors such as group-IV carbides ( SiC , GeC ) and group-III nitrides ( AlN , GaN and BN ) are known to be important materials for novel semiconductor applications. They also have interesting mechanical properties such as having a particularly high value for their bulk modulus and are therefore potential candidates for hard coatings. In this paper we report the theoretical calculations for the bulk modulus for zincblende and wurzite polytypes of these materials. The Density Functional and Total-energy Pseudopotential Techniques in the Generalized Gradient approximation, an ab initio quantum mechanical method, is used to obtain the theoretical structure, from which equilibrium lattice parameters and volume of the cell versus pressure may be extracted. The Murnaghan's equation of state is then used to calculate bulk modulus under elastic deformation, which is related to the hardness of a material under certain conditions. The results for bulk modulus are compared with other theoretical and experimental values reported in the literature.

scholarly journals Performance of a nonempirical exchange functional from density matrix expansion: comparative study with different correlations

2017 ◽  
Vol 19 (32) ◽  
pp. 21707-21713 ◽  
Author(s):  
Yuxiang Mo ◽  
Guocai Tian ◽  
Jianmin Tao
Keyword(s):  
Density Matrix ◽  
Comparative Study ◽  
Correlation Energy ◽  
Generalized Gradient ◽  
Exchange Correlation ◽  
Generalized Gradient Approximation ◽  
Matrix Expansion

Recently, Tao and Mo proposed a meta-generalized gradient approximation for the exchange–correlation energy with remarkable accuracy for molecules, solids, and surfaces.

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