Electronic Structure and Hydrogen Desorption in NaAlH4

ABSTRACTFirst principles calculations based on gradient corrected density functional theory are carried out to understand the electronic structure and mechanisms responsible for desorption of hydrogen from Ti doped and vacancy containing sodium-alanate (NaAlH4). The energy necessary to remove a hydrogen atom from Ti doped NaAlH4 is significantly smaller than that from pristine NaAlH4 irrespective of whether Ti substitutes the Na or the Al site. However, the presence of Na and Al vacancies is shown to play an even more important role: The removal of hydrogen associated with both Na and Al vacancies is found to be exothermic. It is suggested that this role of vacancies can be exploited in the design and synthesis of complex light metal hydrides suitable for hydrogen storage.

Download Full-text

Electronic structure of cubic BaTbO3 from first-principles pseudopotential calculations

Canadian Journal of Physics ◽

10.1139/p06-008 ◽

2006 ◽

Vol 84 (2) ◽

pp. 115-120 ◽

Cited By ~ 3

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

Download Full-text

First-principles study of static displacements in Fe-Pd magnetic shape-memory alloys

MRS Proceedings ◽

10.1557/proc-1200-g04-04 ◽

2009 ◽

Vol 1200 ◽

Cited By ~ 1

Author(s):

Markus E. Gruner

Keyword(s):

Density Functional Theory ◽

Electronic Structure ◽

First Principles ◽

Density Functional ◽

First Principles Calculations ◽

Magnetic Shape Memory ◽

Magnetic Shape Memory Alloys ◽

Functional Theory ◽

Lennard Jones ◽

Theory Comparison

AbstractThis contribution reports static ionic displacements in ferromagnetic disordered Fe70Pd30 alloys obtained by relaxation of the ionic positions of a 108-atom supercell within the framework of density functional theory. Comparison with a simple statistical model based on Lennard-Jones pair interactions reveals that these displacements are significantly larger than can be explained by the different sizes of the elemental constituents. The discrepancies are presumably related to collective displacements of the Fe atoms. Corresponding distortions are experimentally observed for ordered Fe3Pt and predicted by first-principles calculations for all ordered Fe-rich L12 alloys with Ni group elements and originate from details of the electronic structure at the Fermi level.

Download Full-text

Tunable electronic structure and magnetic moment in C2N nanoribbons with different edge functionalization atoms

Physical Chemistry Chemical Physics ◽

10.1039/c7cp01359k ◽

2017 ◽

Vol 19 (23) ◽

pp. 15021-15029 ◽

Cited By ~ 7

Author(s):

Yusheng Wang ◽

Nahong Song ◽

Min Jia ◽

Dapeng Yang ◽

Chikowore Panashe ◽

...

Keyword(s):

Density Functional Theory ◽

Magnetic Properties ◽

Electronic Structure ◽

Magnetic Moment ◽

First Principles ◽

Density Functional ◽

First Principles Calculations ◽

Functional Theory ◽

Electronic And Magnetic Properties

First principles calculations based on density functional theory were carried out to study the electronic and magnetic properties of C2N nanoribbons (C2NNRs).

Download Full-text

First Principles Calculations of Electronic Structure and Optical Properties of Cu-Doped SnS2

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.373-375.1965 ◽

2013 ◽

Vol 373-375 ◽

pp. 1965-1969

Author(s):

Kun Nan Qin ◽

Ling Zhi Zhao ◽

Yong Mei Liu ◽

Fang Fang Li ◽

Chao Yang Cui

Keyword(s):

Optical Properties ◽

Electronic Structure ◽

First Principles ◽

Density Functional ◽

Optical Absorption Coefficient ◽

Impurity Level ◽

First Principles Calculations ◽

Absorption Region ◽

Functional Theory ◽

The Density Functional Theory

The electronic structure and optical properties of Cu-doped SnS2with Sn-substituted content of 0, 12.5 and 37.5 at.% were successfully calculated by the first principles plane-wave pseudopotentials based on the density functional theory. It is found that the intermediate belts appear near the Fermi level and the energy band gap becomes narrower after the doping of the Cu atoms. The absorption peaks show a remarkable redshift and the absorption region broadens relatively after introducing acceptor impurity level. When Sn atoms of 37.5 at% were substituted by Cu, the optical absorption coefficient is significantly improved in the frequency range below 5.58 eV and over 8.13 eV.

Download Full-text

Electronic Structure, Effective Masses and Optical Properties of Monoclinic HfO2 from First-Principles Calculations

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.216.341 ◽

2011 ◽

Vol 216 ◽

pp. 341-344 ◽

Cited By ~ 2

Author(s):

Qi Jun Liu ◽

Zheng Tang Liu ◽

Li Ping Feng

Keyword(s):

Optical Properties ◽

Electronic Structure ◽

Band Structure ◽

First Principles ◽

Density Functional ◽

First Principles Calculations ◽

Functional Theory ◽

Effective Masses ◽

Indirect Band Gap ◽

Calculated Equilibrium

Electronic structure, effective masses and optical properties of monoclinic HfO2were studied using the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory (DFT). The calculated equilibrium lattice parameters are in agreement with the previous works. From the band structure, the effective masses and optical properties are obtained. The calculated band structure shows that monoclinic HfO2has indirect band gap and all of the effective masses of electrons and holes are less than that of a free electron. The peaks position distributions of imaginary parts of the complex dielectric function have been explained according to the theory of crystal-field and molecular-orbital bonding.

Download Full-text

First-principles study of Ga-vacancy induced magnetism in β-Ga2O3

Physical Chemistry Chemical Physics ◽

10.1039/c7cp03675b ◽

2017 ◽

Vol 19 (42) ◽

pp. 28928-28935 ◽

Cited By ~ 4

Author(s):

Ya Yang ◽

Jihua Zhang ◽

Shunbo Hu ◽

Yabei Wu ◽

Jincang Zhang ◽

...

Keyword(s):

Density Functional Theory ◽

Magnetic Properties ◽

Electronic Structure ◽

First Principles ◽

Density Functional ◽

First Principles Calculations ◽

Functional Theory ◽

Cation Vacancies ◽

First Principles Study

First principles calculations based on density functional theory were performed to study the electronic structure and magnetic properties of β-Ga2O3 in the presence of cation vacancies.

Download Full-text

A Density Functional Theory Study of the Catalytic role of Ti atoms in Reversible Hydrogen Storage in the Complex Metal Hydride, NaAlH4

MRS Proceedings ◽

10.1557/proc-884-gg2.1 ◽

2005 ◽

Vol 884 ◽

Author(s):

Santanu Chaudhuri ◽

James T Muckerman

Keyword(s):

Density Functional Theory ◽

First Principles ◽

Molecular Hydrogen ◽

Density Functional ◽

First Principles Calculations ◽

Density Functional Theory Study ◽

Functional Theory ◽

Catalytic Role ◽

Present Part

AbstractPresence of ∼2-4 % Ti is critical for reversible hydrogenation/rehydrogenation in NaAlH4. We have investigated the probable catalytic role of Ti in this complex multi-step process. The present part of our study concentrates on the rehydrogenation reaction, i.e., the reverse reaction that forms NaAlH4 from its constituent binary hydrides. First principles calculations using density functional theory (DFT) show that a particular arrangement of Ti atoms on the surface of Al metal promotes the chemisorption of molecular hydrogen. We also present comparisons with existing experimental data (EXAFS and TEM) to support the existence of such an arrangement on the surface.

Download Full-text

First Principles Study on the Electronic Structure and Optical Properties of La Doped YB6 Crystals

Materials Science ◽

10.5755/j02.ms.25006 ◽

2021 ◽

pp. X

Author(s):

Hongbo TANG ◽

Qiuyue LI ◽

Jian ZHOU ◽

Lihua XIAO ◽

Ping PENG

Keyword(s):

Density Functional Theory ◽

Optical Properties ◽

Electronic Structure ◽

First Principles ◽

Density Functional ◽

Near Infrared ◽

Infrared Light ◽

First Principles Calculations ◽

Functional Theory ◽

La Doped

Received 03 January 2020; accepted 17 June 2020 We have investigated the optical properties of La (0, 0.125, 0.250) doped YB6 by means of first-principles calculations within the framework of density functional theory. It was found that electronic and optical properties of YB6 crystals varied remarkably when Y atoms were replaced with La atoms. Furthermore, with increasing content of La in YB6 crystals from 12.5 % to 25 % reflectivity and absorption coefficient of near infrared light decreased obviously, while the transmittance was enhanced.

Download Full-text

First Principles Calculations of Atomic and Electronic Structure of TiAl3+- and TiAl2+-Doped YAlO3

Materials ◽

10.3390/ma14195589 ◽

2021 ◽

Vol 14 (19) ◽

pp. 5589

Author(s):

Sergei Piskunov ◽

Aleksejs Gopejenko ◽

Vladimir Pankratov ◽

Inta Isakoviča ◽

Chong-Geng Ma ◽

...

Keyword(s):

Electronic Structure ◽

First Principles ◽

Density Functional ◽

First Principles Calculations ◽

Functional Theory ◽

Interatomic Distances ◽

Atomic Orbitals ◽

The Density Functional Theory ◽

F Center ◽

Atomic And Electronic Structure

In this paper, the density functional theory accompanied with linear combination of atomic orbitals (LCAO) method is applied to study the atomic and electronic structure of the Ti3+ and Ti2+ ions substituted for the host Al atom in orthorhombic Pbnm bulk YAlO3 crystals. The disordered crystalline structure of YAlO3 was modelled in a large supercell containing 160 atoms, allowing simulation of a substitutional dopant with a concentration of about 3%. In the case of the Ti2+-doped YAlO3, compensated F-center (oxygen vacancy with two trapped electrons) is inserted close to the Ti to make the unit cell neutral. Changes of the interatomic distances and angles between the chemical bonds in the defect-containing lattices were analyzed and quantified. The positions of various defect levels in the host band gap were determined.

Download Full-text

Core properties and the role of screw dislocations in the bulk n-type conductivity in InN

Physical Chemistry Chemical Physics ◽

10.1039/c9cp02062d ◽

2019 ◽

Vol 21 (28) ◽

pp. 15767-15778

Author(s):

Imad Belabbas ◽

Laurent Pizzagalli ◽

Joseph Kioseoglou ◽

Jun Chen

Keyword(s):

Density Functional Theory ◽

First Principles ◽

Density Functional ◽

Indium Nitride ◽

First Principles Calculations ◽

Functional Theory ◽

Screw Dislocations ◽

Type Conductivity

First principles calculations, based on density functional theory, have been carried out to investigate the role of screw dislocations in the bulk n-type conductivity which is usually observed in indium nitride.

Download Full-text