scholarly journals Ab initio aided design of novel quaternary, quinary and senary high-entropy borocarbides

2022 ◽  
Author(s):  
Daniel Hedman ◽  
Ana C. Feltrin ◽  
Yoshiyuki Miyamoto ◽  
Farid Akhtar
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Configurational Entropy ◽  
Density Functional Theory Calculations ◽  
Single Element ◽  
Anion Sublattice ◽  
High Entropy ◽  
Directional Preference ◽  
Lattice Distortions ◽  
Aided Design

AbstractHigh-entropy materials have attracted considerable interest due to their unique, improved properties and large configurational entropy. Out of these, high-entropy ceramics (HECs) are of particular interest since the independent solubility of cations and anions results in increased configurational entropy. However, most HEC research considers only a single element occupying the anion sublattice, which limits the maximum attainable configurational entropy. Here, we expand our previous work on high-entropy borocarbides where both boron and carbon occupy the anion sublattice. By applying an ab initio based screening procedure, we identify six elements Li, Ti, V, Zr, Nb and Hf suitable for forming high-entropy borocarbides. With these elements, we propose six novel HEC compositions, and by computing their entropy forming ability, we identify that three are likely to form single-phase during synthesis. Material properties and lattice distortions for all proposed compositions are studied using density functional theory calculations with special quasirandom structures. The directional lattice distortions, a concept we introduce in this work, show that lattice distortions have an elemental and directional preference for certain HEC compositions. We also show that the novel inclusion of Li improves the mechanical properties of the proposed HECs, the details of which are studied using the electron localization function.

Ab Initio Calculation of Mechanical Properties of Stacking Fault in 3C-SiC: Effect of Stress and Doping

2012 ◽  
Vol 717-720 ◽  
pp. 415-418
Author(s):  
Yoshitaka Umeno ◽  
Kuniaki Yagi ◽  
Hiroyuki Nagasawa
Keyword(s):  
Mechanical Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Stacking Faults ◽  
Single Layer ◽  
Local Strain ◽  
Density Functional Theory Calculations ◽  
Stacking Fault ◽  
Functional Theory ◽  
N Doping

We carry out ab initio density functional theory calculations to investigate the fundamental mechanical properties of stacking faults in 3C-SiC, including the effect of stress and doping atoms (substitution of C by N or Si). Stress induced by stacking fault (SF) formation is quantitatively evaluated. Extrinsic SFs containing double and triple SiC layers are found to be slightly more stable than the single-layer extrinsic SF, supporting experimental observation. Effect of tensile or compressive stress on SF energies is found to be marginal. Neglecting the effect of local strain induced by doping, N doping around an SF obviously increase the SF formation energy, while SFs seem to be easily formed in Si-rich SiC.

Magnetic Phase Diagram of Transition Metal Doped ZnO from Density Functional Theory Calculations and Monte Carlo Simulations

2010 ◽  
Vol 1260 ◽  
Author(s):  
Sanjeev K. Nayak ◽  
Heike C. Herper ◽  
Peter Entel
Keyword(s):  
Monte Carlo ◽  
Curie Temperature ◽  
Monte Carlo Simulations ◽  
Ab Initio ◽  
Density Functional ◽  
Magnetic Phase Diagram ◽  
Density Functional Theory Calculations ◽  
Antiferromagnetic Coupling ◽  
Doped Zno ◽  
Co Concentrations

AbstractTransition metals doped ZnO are possible candidates for multiferroics. Here, we have investigated the evolution of ferromagnetism due to Co dopants. The magnetic properties have been studied for Co concentrations from 0 to 100% by using ab-initio methods, i.e., KKR Green's function techniques. In order to estimate the Curie temperature we have performed Monte Carlo simulations with ab-initio calculated exchange parameters.From our calculations the onset of ferromagnetism occurs between 5 to 20% of Co depending on the numerical details of KKR method used. For Co concentrations larger than 50% the system is dominated by antiferromagnetic coupling and no Curie temperature can be obtained.

scholarly journals Solvent Effect on the Structure and Properties of RGD Peptide (1FUV) at Body Temperature (310 K) Using Ab Initio Molecular Dynamics

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3434
Author(s):  
Khagendra Baral ◽  
Puja Adhikari ◽  
Bahaa Jawad ◽  
Rudolf Podgornik ◽  
Wai-Yim Ching
Keyword(s):  
Molecular Dynamics ◽  
Body Temperature ◽  
Ab Initio ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Rgd Peptide ◽  
Ab Initio Molecular Dynamics ◽  
Quantum Mechanical ◽  
Aqueous Environment ◽  
Structure And Properties

The structure and properties of the arginine-glycine-aspartate (RGD) sequence of the 1FUV peptide at 0 K and body temperature (310 K) are systematically investigated in a dry and aqueous environment using more accurate ab initio molecular dynamics and density functional theory calculations. The fundamental properties, such as electronic structure, interatomic bonding, partial charge distribution, and dielectric response function at 0 and 310 K are analyzed, comparing them in dry and solvated models. These accurate microscopic parameters determined from highly reliable quantum mechanical calculations are useful to define the range and strength of complex molecular interactions occurring between the RGD peptide and the integrin receptor. The in-depth bonding picture analyzed using a novel quantum mechanical metric, the total bond order (TBO), quantifies the role played by hydrogen bonds in the internal cohesion of the simulated structures. The TBO at 310 K decreases in the dry model but increases in the solvated model. These differences are small but extremely important in the context of conditions prevalent in the human body and relevant for health issues. Our results provide a new level of understanding of the structure and properties of the 1FUV peptide and help in advancing the study of RGD containing other peptides.

scholarly journals Two-dimensional Dirac fermions on oxidized black phosphorus

2019 ◽  
Vol 21 (43) ◽  
pp. 24206-24211
Author(s):  
Seoung-Hun Kang ◽  
Jejune Park ◽  
Sungjong Woo ◽  
Young-Kyun Kwon
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Black Phosphorus ◽  
Inversion Symmetry ◽  
Dirac Fermions ◽  
Two Dimensional ◽  
Functional Theory

Using ab initio density functional theory calculations, we find four-fold degenerate Dirac points protected by two nonsymmorphic symmetries in phosphorene oxide with the inversion symmetry broken.

scholarly journals Ab initio study of elastic anisotropies and thermal conductivities of rhenium diborides in different crystal structures

RSC Advances ◽  
2020 ◽  
Vol 10 (61) ◽  
pp. 37142-37152
Author(s):  
Yi X. Wang ◽  
Ying Y. Liu ◽  
Zheng X. Yan ◽  
W. Liu ◽  
Jian B. Gu
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Crystal Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Ab Initio Study ◽  
Ambient Conditions ◽  
Functional Theory ◽  
Thermal Conductivities

The phase stabilities, elastic anisotropies, and thermal conductivities of ReB2 diborides under ambient conditions have been investigated by using density functional theory calculations.

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