scholarly journals Introduction to first-principles electronic structure methods: Application to actinide materials

2006 ◽  
Vol 21 (12) ◽  
pp. 2979-2985 ◽  
Author(s):  
John E. Klepeis
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Background Information ◽  
Quantum Molecular Dynamics ◽  
Generalized Gradient ◽  
Sufficient Detail ◽  
Current Controversy ◽  
Electronic Structure Methods

This paper provides an introduction for non-experts to first-principles electronic structure methods that are widely used in condensed-matter physics. Particular emphasis is placed on giving the appropriate background information needed to better appreciate the use of these methods to study actinide and other materials. Specifically, the underlying theory is described in sufficient detail to enable an understanding of the relative strengths and weaknesses of the methods. In addition, the meaning of commonly used terminology is explained, including density functional theory (DFT), local density approximation (LDA), and generalized gradient approximation (GGA), as well as linear muffin-tin orbital (LMTO), linear augmented plane wave (LAPW), and pseudopotential methods. Methodologies that extend the basic theory to address specific limitations are also briefly discussed. Finally, a few illustrative applications are presented, including quantum molecular dynamics (QMD) simulations and studies of surfaces, impurities, and defects. The paper concludes by addressing the current controversy regarding magnetic calculations for actinide materials.

scholarly journals Introduction to First-Principles Electronic Structure Methods: Application to Actinide Materials

2005 ◽  
Vol 893 ◽  
Author(s):  
John E Klepeis
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Condensed Matter ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Current Controversy ◽  
Electronic Structure Methods

AbstractThe purpose of this paper is to provide an introduction for non-experts to first-principles electronic structure methods that are widely used in the field of condensed-matter physics, including applications to actinide materials. The methods I describe are based on density functional theory (DFT) within the local density approximation (LDA) and the generalized gradient approximation (GGA). In addition to explaining the meaning of this terminology I also describe the underlying theory itself in some detail in order to enable a better understanding of the relative strengths and weaknesses of the methods. I briefly mention some particular numerical implementations of DFT, including the linear muffin-tin orbital (LMTO), linear augmented plane wave (LAPW), and pseudopotential methods, as well as general methodologies that go beyond DFT and specifically address some of the weaknesses of the theory. The last third of the paper is devoted to a few selected applications that illustrate the ideas discussed in the first two-thirds. In particular, I conclude by addressing the current controversy regarding magnetic DFT calculations for actinide materials. Throughout this paper particular emphasis is placed on providing the appropriate background to enable the non-expert to gain a better appreciation of the application of first-principles electronic structure methods to the study of actinide and other materials.

Magnetic Properties of Embedded Rh Clusters in Ni Matrix

1995 ◽  
Vol 384 ◽  
Author(s):  
Zhi-Qiang Li ◽  
Yuichi Hashi ◽  
Jing-Zhi Yu ◽  
Kaoru Ohno ◽  
Yoshiyuki Kawazoe
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Magnetic Moments ◽  
Functional Formalism ◽  
Rhodium Clusters ◽  
Spin Polarized ◽  
Local Density Functional

ABSTRACTThe electronic structure and magnetic properties of rhodium clusters with sizes of 1 - 43 atoms embedded in the nickel host are studied by the first-principles spin-polarized calculations within the local density functional formalism. Single Rh atom in Ni matrix is found to have magnetic moment of 0.45μB. Rh13 and Rhl 9 clusters in Ni matrix have lower magnetic moments compared with the free ones. The most interesting finding is tha.t Rh43 cluster, which is bulk-like nonmagnetic in vacuum, becomes ferromagnetic when embedded in the nickel host.

Structural, elastic and thermodynamic properties of A15-type compounds V3X (X = Ir, Pt and Au) from first-principles calculations

2016 ◽  
Vol 30 (35) ◽  
pp. 1650414 ◽  
Author(s):  
Mingliang Wang ◽  
Zhe Chen ◽  
Dong Chen ◽  
Cunjuan Xia ◽  
Yi Wu
Keyword(s):  
Thermodynamic Properties ◽  
Debye Temperature ◽  
First Principles ◽  
Density Functional ◽  
Coefficient Of Thermal Expansion ◽  
Local Density ◽  
Debye Model ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Experimental Values

The structural, elastic and thermodynamic properties of the A15 structure V3Ir, V3Pt and V3Au were studied using first-principles calculations based on the density functional theory (DFT) within generalized gradient approximation (GGA) and local density approximation (LDA) methods. The results have shown that both GGA and LDA methods can process the structural optimization in good agreement with the available experimental parameters in the compounds. Furthermore, the elastic properties and Debye temperatures estimated by LDA method are typically larger than the GGA methods. However, the GGA methods can make better prediction with the experimental values of Debye temperature in V3Ir, V3Pt and V3Au, signifying the precision of the calculating work. Based on the E–V data derived from the GGA method, the variations of the Debye temperature, coefficient of thermal expansion and heat capacity under pressure ranging from 0 GPa to 50 GPa and at temperature ranging from 0 K to 1500 K were obtained and analyzed for all compounds using the quasi-harmonic Debye model.

Electronic structure of cubic BaTbO3 from first-principles pseudopotential calculations

2006 ◽  
Vol 84 (2) ◽  
pp. 115-120 ◽  
Author(s):  
G Y Gao ◽  
K L Yao ◽  
Z L Liu
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Pseudopotential Calculations ◽  
Correlation Potential ◽  
Density Contour

First-principles calculations of the electronic structure are performed for cubic BaTbO3 using the plane-wave pseudopotential method within the framework of density functional theory and using the generalized gradient approximation for the exchange-correlation potential. Our calculations show that cubic BaTbO3 is metallic, and that this metallic character is mainly governed by the Tb 4f electrons and the hybridization between the Tb 5d and O 2p states. From the analysis of the density of states, band structure, and charge density contour, we find that the chemical bonding between Tb and O is covalent while that between Ba and TbO3 is ionic. PACS Nos.: 71.15.Mb, 71.20.-b

scholarly journals Structural and Electronic Properties of Orthorhombic Phase Bi2Se3 Based On First-Principles Study

2019 ◽  
Vol 16 (2) ◽  
pp. 77 ◽  
Author(s):  
Muhammad Zamir Mohyedin ◽  
Afiq Radzwan ◽  
Mohammad Fariz Mohamad Taib ◽  
Rosnah Zakaria ◽  
Nor Kartini Jaafar ◽  
...  
Keyword(s):  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Computer Code ◽  
First Principles Calculation ◽  
Generalized Gradient ◽  
Exchange Correlation ◽  
Percentage Difference ◽  
Structural And Electronic Properties

Bi2Se3 is one of the promising materials in thermoelectric devices and very useful out of environmental concern due to its efficiency to perform at room temperature. Based on the first-principles calculation of density functional theory (DFT) by using CASTEP computer code, structural and electronic properties of Bi2Se3 were investigated. The calculation is conducted within the exchange-correlation of local density approximation (LDA) and generalized gradient approximation within the revision of Perdew-Burke-Ernzerhof (GGA-PBE) functional. It was found that the results are consistent with previous works of theoretical study with small percentage difference. LDA exchange-correlation functional method is more accurate and have a better agreement than GGA-PBE to describe the structural properties of Bi2Se3 which consist of lattice parameters. LDA functional also shown more accurate electronic structure of Bi2Se3 that consist of band structure and density of states (DOS) which consistent with most previous theoretical works with small percentage difference. This study proves the reliability of CASTEP computer code and show LDA exchange-correlation functional is more accurate in describing the nature of Bi2Se3 compared to the other functionals.

First Principles Calculations for Metal/Ceramic Interfaces

1994 ◽  
Vol 357 ◽  
Author(s):  
M. W. Finnis ◽  
C. Kruse ◽  
U. SchÖnberger
Keyword(s):  
Electronic Structure ◽  
High Resolution ◽  
Ab Initio ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Work Of Adhesion ◽  
First Principles Calculations ◽  
Resolution Electron ◽  
Metal Ceramic

AbstractWe discuss the recent first principles calculations of the properties of interfaces between metals and oxides. This type of calculation is parameter-free, and exploits the density functional theory in the local density approximation to obtain the electronic structure of the system. At the same time the equilibrium atomic structure is sought, which minimises the excess energy of the interface. Up to now calculations of this type have been made for a few model interfaces which are atomically coherent, that is with commensurate lattices. Examples are Ag/MgO and Nb/Al2O3. In these cases it has been possible to predict the structures observed by high resolution electron microscopy. The calculations are actually made in a supercell geometry, in which there are alternating nanolayers of metal and ceramic. Because of the effectiveness of metallic screening in particular, the interfaces between the nanolayers do not interfere much with each other.Besides the electronic structure of the interface, such calculations have provided values of the ideal work of adhesion. Electrostatic image forces in conjunction with the elementary ionic model provide a simple framework for understanding the results.An important role of such calculations is to develop intuition about the nature of the bonding, including the effects of charge transfer, which has formerly only been described in an empirical way. It may then be possible to build atomistic models of the metal/ceramic interaction which have a sound physical basis and can be calibrated against ab initio results. Simpler models are necessary if larger systems, including misfit dislocations and other defects, are to be simulated, with a view to understanding the atomic processes of growth and failure. Another area in which ab initio calculations can be expected to contribute is in the chemistry of impurity segregation and its effect at interfaces. Such theoretical tools are a natural partner to the experimental technique of high resolution electron energy loss spectroscopy for studying the local chemical environment at an interface.

Possidle Isomers and Electronic Structure of C60H36

1990 ◽  
Vol 206 ◽  
Author(s):  
B. I. Dunlap ◽  
D. W. Brenner ◽  
R. C. Mowrey ◽  
J. W. Mintmire ◽  
D. H. Robertson ◽  
...  
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
High Symmetry ◽  
Hydrogen Atoms ◽  
Functional Methods ◽  
Metastable Structure ◽  
Total Energies ◽  
Rice University

ABSTRACTNewly developed empirical hydrocarbon potentials and self-consistent first-principles local density functional methods are used to investigate possible isomers and the electronic structure of C60H36. Within the high symmetry Th structure conjectured by the groups at Rice University there are two inequivalent sets of hydrogen atoms containing twelve and twenty-four atoms respectively. Binding each set either inside or outside of the C60 cage leads to four isomers of C60H36 with inequivalent strain energies. Although we find that placing twelve hydrogens inside the cage can lead to a metastable structure, our calculated total energies suggest that the isomer with all the hydrogens on the outside of the cage is the energetically most stable.

Electronic structure, optical and thermodynamic properties of ternary hydrides MBeH3 (M = Li, Na, and K)

2016 ◽  
Vol 94 (9) ◽  
pp. 865-876 ◽  
Author(s):  
Dj Guendouz ◽  
Z. Charifi ◽  
H. Baaziz ◽  
T. Ghellab ◽  
N. Arikan ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Thermodynamic Properties ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Debye Model ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Electron Charge Density ◽  
Principal Aspect

Electronic band structure, optical and thermodynamic properties of ternary hydrides MBeH3 (M = Li, Na, and K) were studied using ab initio density functional theory (DFT). The effect of the adopted approximation to the exchange-correlation functional of the DFT is explicitly investigated by considering four different expressions of two different classes (local-density approximation and generalized-gradient approximation). The calculated magnitude of B classifies MBeH3 (M = Li, Na, and K) as easily compressible materials. The bonding interaction in these compounds is quite complicated. The interaction between M and BeH6 is ionic and that between Be and H comprises both ionic and covalent characters. The electronic structure of the complex hydride was investigated by calculating the partial and total densities of states, and electron charge density distribution. Large gaps in the density of states appear at the Fermi energy of LiBeH3, NaBeH3, and KBeH3 indicating that these classes of hydrides are insulators. Optical properties, including the dielectric function, reflectivity, and absorption coefficient, each as a function of photon energy, are calculated and show an optical anisotropy for LiBeH3 and KBeH3. Through the quasi-harmonic Debye model, in which the phononic effects are considered, temperature dependence of volume V(T), bulk modulus B(T), and thermal expansion coefficient α(T), constant-volume and constant-pressure specific heat (Cv and Cp) and Debye temperature ΘD, the entropy S, and the Grüneisen parameter γ were calculated at wide pressure and temperature ranges. The principal aspect of the obtained results is the close similarity of MBeH3 (M = Li, Na, and K) compounds.

First-principles study of electronic and optical properties of Sr2ZnN2 under pressure

2016 ◽  
Vol 30 (10) ◽  
pp. 1650139
Author(s):  
Kai Liang ◽  
Hui Zhao
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Electronic Structure ◽  
Dielectric Function ◽  
First Principles ◽  
Density Functional ◽  
Optical Transition ◽  
Dft Method ◽  
Structural Parameter ◽  
Generalized Gradient

First-principles calculations of ternary Sr2ZnN2 compound using density-functional theory (DFT) method within the generalized gradient approximation (GGA) has been performed. Based on the optimized structural parameter, the electronic properties and optical properties have been researched. The calculated lattice constants are in agreement with the experimental and theoretical results. The electronic structure have been investigated throughout the calculated band structure and density of states (DOS). It shows that this compound belongs to the semiconductors with a band gap of about 0.775[Formula: see text]eV. Furthermore, in order to clarify the optical transition of this material, the optical properties such as dielectric function, absorption coefficient, reflectivity, refractive index and energy-loss function at different pressures of 0, 10 and 20[Formula: see text]GPa in the energy range 0–20[Formula: see text]eV were performed and discussed. It shows that Sr2ZnN2 is a strong anisotropy material and the imaginary part of dielectric function shifts to higher energy region as the pressure increases. The square of calculated static refractive index is equal to static dielectric function, which corresponds to the theory formula. In conclusion, pressure is a effective method to change the electronic structure and optical properties.

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