Density Function Theory Calculation of Crystal Properties and Electronic Structure of δ-Pu

2017 ◽  
Vol 727 ◽  
pp. 712-717
Author(s):  
Yuan Jiang Zhu ◽  
Yun Liang Gao

In this paper, lattice constants, elastic properties and electronic structure of δ-Pu are investigated by means of plane wave pseudo-potential method (PWP) based on density function theory (DFT). A variety of density functional theory methods have been adopted to calculate the crystal structure and elastic property of δ-Pu, and it is found that the lattice constants, bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν calculated by spin polarization local density approximation (SP+LDA) method are in best agreement with experimental values. The electronic structure have been investigated within the framework of LDA+U, and the band structure, density of state (DOS) and partial density of state (PDOS) are calculated. Calculation results of elastic properties and electronic structure show that, δ-Pu shows obvious metallicity and well ductility, its electrons are strongly corrected and the DOS in the vicinity of the Fermi Level is mainly contributed by 5f electrons.

Author(s):  
Chunhai Lu ◽  
Wenkai Chen ◽  
Min Chen ◽  
Shijun Ni ◽  
Chengjiang Zhang

The local-density approximation (LDA) coupled with the virtual crystal approximation (VCA) method electronic structure is applied to evaluate elastic constants, bulk modulus, shear modulus, Young’s modulus and Poisson’s ratio mechanic properties of metal zirconium, Zircaloy-2 and Zircaloy-4. The results show that there is no obvious difference in band structure and total density of state (DOS) between metal zirconium and zirconium alloy. However, p and d electron partial density of state (PDOS) presents the slight difference between metal zirconium and zirconium alloy. Zircaloy-2 and Zircaloy-4 present better elastic mechanical properties than metal zirconium. The metal zirconium and zirconium alloy show the anisotropic mechanical properties.


2012 ◽  
Vol 624 ◽  
pp. 117-121 ◽  
Author(s):  
Fan Jun Zeng ◽  
Qing Lin Xia

The electronic structure, chemical bonding and elastic properties of Ti3AC2 (A=Al, Si, Sn) were investigated by generalized gradient approximation (GGA) based on density functional theory (DFT). The calculated lattice parameters and equilibrium volumes are in good agreement with the available experimental data. The density of state (DOS) and partial density of states (PDOS) show that the DOS at the Fermi level (EF) is located at the bottom of a valley and originate mainly from the Ti-3d electrons. Population analyses suggest that there are strong covalent bonding in Ti1-C and Ti2-C atoms in Ti3AC2 (A=Al, Si, Sn). Single-crystal elasticity constants were calculated and the polycrystalline elastic modules were estimated according to Voigt, Reuss and Hill’s approximations (VRH). The Young’s modulus Y, Poisson’s ratio ν and BH/GH are also predicted. Results conclude that the hexagonal phase Ti3AC2 (A=Al, Si, Sn) are mechanical stable and behaves in a brittle manner. Polycrystalline elastic anisotropy coefficients AB and AG are also derived from polycrystalline bulk modulus B and shear modulus G.


2020 ◽  
Vol 20 (3) ◽  
pp. 1651-1659 ◽  
Author(s):  
Hongmei Zhu ◽  
Zhengjie Zhang ◽  
Xuchuan Jiang

Density function theory (DFT) method was developed and applied for fundamentally understanding the doping effect of various metals (Al, Ti and Cr) on vanadium dioxide (VO2). The substitution doping of Al, Ti and Cr in VO2 could lead to significant changes in electronic structure, band gap and optical property. Different from physical experiments, the DFT method could be utilized for fundamental understandings at an atomic scale. It was found via DFT calculations that: (i) Al doping caused a slightly distorted octahedron in monoclinic VO2(M), and narrowed the band gap of VO2(M) due to the upward shift of the valence band (VB), while Cr doping narrowed the band gap because of the downward shift of the conduction band (CB); (ii) Ti doping slightly widened the band gap of VO2(M); and (iii) the optical reflectivity of VO2(M) decreased after substitution doping low-valent metals (e.g., Al). This study will be beneficial for designing and controlling elemental doping to obtain metal oxide nanocomposites with unique band gap and electronic structure for thermochromic energy saving applications.


2008 ◽  
Vol 575-578 ◽  
pp. 612-615
Author(s):  
Hong Tao Cheng ◽  
Jian Guo Yang ◽  
Hong Yuan Fang

The properties of different Cu surface were studied by the pseudo-potentials method based on density function theory. The lattice constant obtained with GGA(Generalized Gradient Approximation) is close to the experimental values than that with LDA(Local Density Approximation), so we adopt the GGA to simulate the cohesive energies and the surface energies of the Cu(100), Cu(110) and Cu(111) surface. The simulated results are shown to be in agreement with the macroscopic validity of the experimental measurements.


2012 ◽  
Vol 516-517 ◽  
pp. 1889-1892 ◽  
Author(s):  
Xiu Rong Zhang ◽  
Lin Yin ◽  
Wei Jun Li ◽  
Hui Shuai Tang

The geometric structures of PtNN0,± clusters are optimized by the B3LYP/LANL2DZ method of density function theory, the ground state structures are obtained, and the electronic structure are studied. The results show: the N atoms gain the charge when the clusters are formed, but some Pt atoms gain the charge and other Pt atoms lose the charge. N atom and Pt atom have internal heterozygous, and the spd hybridized between Pt atoms and N atoms are increasing with cluster s’ sizes.


2021 ◽  
Vol 67 (2 Mar-Apr) ◽  
pp. 299
Author(s):  
M. Tedjani

In this theoretical study, we presents  for the first time, to the best of our knowledge, the structural, electronic and elastic properties of perovskite Sr0.5Be0.5TiO3 type structure (Tetragonal), P4/mmm, space group, 123.using full potential linearized augmented plane wave (FP-LAPW) method on the basis of density functional theory (DFT) integrated in the Wien2k code . The generalized gradient approximation (GGA-PBEsol) and local density approximation has been used for the exchange correlation potential .The electronic properties represented by the band structure (BS) and DOS as well as the (PDOS) partial density of states, allowed to obtain  semiconductor compound, which have been calculated with mBJ approximation. The elastic constants were reported and we verified the stability conditions of our materials elastically. These theoretical results open the way for experimental and other theoretical studies of this compound.


2017 ◽  
Vol 16 (04) ◽  
pp. 1750036
Author(s):  
Xiyuan Sun ◽  
Jiguang Du

The structures, electronic properties, bonding characters and UV–Vis spectra of [Formula: see text] ([Formula: see text]–[Formula: see text]) transition-metal phthalocyanines (TMPcs) molecules have been studied with different density function theory (DFT) methods. The calculated structural parameters agree well with previous experimental or theoretical values. Natural Population Analysis (NPA) charge revealed that [Formula: see text]–[Formula: see text] hybridizations occur when [Formula: see text] TM atoms are involved in chemical bondings. The spin magnetic moments of TMPcs are mainly from the contribution of [Formula: see text] electrons. Conceptual density functional theory (CDFT) results indicate that [Formula: see text] TMPcs molecules are willing to accept further electrons. The TM–N chemical bonds show very weak covalent nature, and are consistent with bond order analyses. Time-dependent density function theory (TD-DFT) calculations were carried out to simulate the UV–Vis spectra, and corresponding electronic transfers for dominant peaks were also obtained.


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