Correct Structural Phase Stability of FeS2, TiO2, and MnO2 from a Semilocal Density Functional

2021 ◽  
Vol 125 (7) ◽  
pp. 4284-4291
Author(s):  
Bikash Patra ◽  
Subrata Jana ◽  
Lucian A. Constantin ◽  
Prasanjit Samal
Keyword(s):  
Phase Stability ◽  
Density Functional ◽  
Structural Phase

scholarly journals Phase Stability in heavy f-Electron Metals from First-Principles Theory

2005 ◽  
Vol 893 ◽  
Author(s):  
Per Söderlind
Keyword(s):  
Phase Stability ◽  
Density Functional ◽  
Structural Phase ◽  
New Physics ◽  
Functional Theory ◽  
Higher Symmetry ◽  
Peierls Distortion ◽  
Breaking Mechanism ◽  
Ground State Structures ◽  
Volume Range

AbstractThe structural phase stability of heavy f-electron metals is studied by means of density-functional theory (DFT). These include temperature-induced transitions in plutonium metal as well as pressure-induced transitions in the trans-plutonium metals Am, Cm, Bk, and Cf. The early actinides (Th-Np) display phases that could be rather well understood from the competition of a crystal-symmetry breaking mechanism (Peierls distortion) of the 5f states and electrostatic forces, while for the trans-plutonium metals (Am-Cf) the ground-state structures are governed by 6d bonding. We show in this paper that new physics is needed to understand the phases of the actinides in the volume range of about 15-30 Å3. At these volumes one would expect, from theoretical arguments made in the past, to encounter highly complex crystal phases due to a Peierls distortion. Here we argue that the symmetry reduction associated with spin polarization can make higher symmetry phases competitive. Taking this into account, DFT is shown to describe the well-known phase diagram of plutonium and also the recently discovered complex and intriguing high-pressure phase diagrams of Am and Cm. The theory is further applied to investigate the behaviors of Bk and Cf under compression.

Systematics of Structural, Phase Stability, and Cohesive Properties of η′-Cu6(Sn,In)5 Compounds Occurring in In-Sn/Cu Solder Joints

2017 ◽  
Vol 46 (7) ◽  
pp. 4485-4496 ◽  
Author(s):  
S. B. Ramos ◽  
N. V. González Lemus ◽  
C. E. Deluque Toro ◽  
G. F. Cabeza ◽  
A. Fernández Guillermet
Keyword(s):  
Phase Stability ◽  
Solder Joints ◽  
Structural Phase ◽  
Cohesive Properties

scholarly journals Electronic structure, Mechanical and Thermodynamic properties of CoYSb (Y= Cr, Mo, W) half-Heusler compounds as potential spintronic materials

2021 ◽  
Author(s):  
O. T. Uto ◽  
J. O. Akinlami ◽  
S. Kenmoe ◽  
G. A. Adebayo
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Structural Phase ◽  
Covalent Bond ◽  
Stable Phase ◽  
Type I ◽  
Generalized Gradient ◽  
Electronic Density ◽  
Electronic Band ◽  
Half Metallic

Abstract The CoYSb (Y = Cr, Mo and W) compounds which are XYZ type half-Heusler alloys and also exist in the face centred cubic MgAgAs-type struc-ture conform to F ̄43m space group. In the present work, these compoundsare investigated in different atomic arrangements called, Type-I, Type-II andType-III phases, using Generalized Gradient Approximation (GGA) in the Density Functional Theory (DFT) implemented in QE (Quantum EspressoAb-Initio Simulation Package). The ferromagnetic state of these alloys is studied after investigating their stable structural phase. The calculated electronic band structure and the total electronic density of states indicated nearly half-metallic behaviour in CoMoSb with a possibility of being used in spintronic application, metallic in CoWSb and half-metallic in CoCrSb, with the minority spin band gap of 0.81 eV. Furthermore, the calculated mechanical properties predicted an anisotropic behaviour of these alloys in the stable phase. Finally, due to its high Debye temperature value, CoCrSb possesses a stronger covalent bond than CoMoSb and CoWSb, respectively.

scholarly journals Unlocking surface octahedral tilt in two-dimensional Ruddlesden-Popper perovskites

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Yan Shao ◽  
Wei Gao ◽  
Hejin Yan ◽  
Runlai Li ◽  
Ibrahim Abdelwahab ◽  
...  
Keyword(s):  
Density Functional ◽  
Carrier Transport ◽  
Plane Surface ◽  
Structural Phase ◽  
Density Functional Theory Calculations ◽  
Spin Splitting ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Out Of Plane ◽  
Inversion Asymmetry

AbstractMolecularly soft organic-inorganic hybrid perovskites are susceptible to dynamic instabilities of the lattice called octahedral tilt, which directly impacts their carrier transport and exciton-phonon coupling. Although the structural phase transitions associated with octahedral tilt has been extensively studied in 3D hybrid halide perovskites, its impact in hybrid 2D perovskites is not well understood. Here, we used scanning tunneling microscopy (STM) to directly visualize surface octahedral tilt in freshly exfoliated 2D Ruddlesden-Popper perovskites (RPPs) across the homologous series, whereby the steric hindrance imposed by long organic cations is unlocked by exfoliation. The experimentally determined octahedral tilts from n = 1 to n = 4 RPPs from STM images are found to agree very well with out-of-plane surface octahedral tilts predicted by density functional theory calculations. The surface-enhanced octahedral tilt is correlated to excitonic redshift observed in photoluminescence (PL), and it enhances inversion asymmetry normal to the direction of quantum well and promotes Rashba spin splitting for n > 1.

scholarly journals Theoretical design of a technetium-like alloy and its catalytic properties

2019 ◽  
Vol 10 (21) ◽  
pp. 5461-5469
Author(s):  
Wei Xie ◽  
Michihisa Koyama
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Catalytic Activity ◽  
Density Of States ◽  
Phase Stability ◽  
Density Functional ◽  
Catalytic Properties ◽  
Functional Theory ◽  
Theoretical Design ◽  
Structure Phase

Based on the concept of density of states (DOS) engineering, we theoretically designed a pseudo-Tc material (Mo–Ru alloy) and investigated its electronic structure, phase stability and catalytic activity by using density functional theory.

First-principles study of phase stability, electronic and mechanical properties of plutonium sub-oxides

2019 ◽  
Vol 21 (30) ◽  
pp. 16818-16829 ◽  
Author(s):  
P. S. Ghosh ◽  
A. Arya
Keyword(s):  
Mechanical Properties ◽  
Density Functional Theory ◽  
Phase Stability ◽  
First Principles ◽  
Density Functional ◽  
Functional Theory ◽  
First Principles Study ◽  
Hubbard Parameter ◽  
Formation Energies

Formation energies of PuO2, α-Pu2O3 and sub-oxides PuO2−x (0.0 < x < 0.5) are determined using density functional theory employing generalised gradient approximation corrected with an effective Hubbard parameter.

Density functional study of the phase stability and Raman spectra of Yb2O3, Yb2SiO5 and Yb2Si2O7 under pressure

2018 ◽  
Vol 20 (24) ◽  
pp. 16518-16527 ◽  
Author(s):  
Takafumi Ogawa ◽  
Noriko Otani ◽  
Taishi Yokoi ◽  
Craig A. J. Fisher ◽  
Akihide Kuwabara ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrostatic Pressure ◽  
Raman Spectra ◽  
Phase Stability ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Study ◽  
Functional Theory ◽  
Density Functional Study

The phase stability and Raman spectra of Yb2O3, Yb2SiO5 and Yb2Si2O7 under hydrostatic pressure are investigated using density functional theory calculations.

Theoretical study of gas and solvent phase stability and molecular adsorption of noncanonical guanine bases on graphene

2017 ◽  
Vol 19 (25) ◽  
pp. 16819-16830 ◽  
Author(s):  
Nabanita Saikia ◽  
Shashi P. Karna ◽  
Ravindra Pandey
Keyword(s):  
Density Functional Theory ◽  
Phase Stability ◽  
Density Functional ◽  
Theoretical Study ◽  
Molecular Adsorption ◽  
Functional Theory ◽  
Solvent Phase

The gas and solvent phase stability of noncanonical (Gua)n nucleobases is investigated in the framework of dispersion-corrected density functional theory (DFT).

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