The dataset of covalent bond lengths resulting from the first-principle calculations

2019 ◽  
Vol 1163 ◽  
pp. 112508 ◽  
Author(s):  
Tymofii Yu. Nikolaienko ◽  
Valerii S. Chuiko ◽  
Leonid A. Bulavin
Keyword(s):  
Covalent Bond ◽  
First Principle ◽  
Bond Lengths ◽  
First Principle Calculations

scholarly journals Effect of Nb on the Microstructure and Mechanical Properties of Ti2Cu Intermetallic through the First-Principle Calculations and Experimental Investigation

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 547 ◽  
Author(s):  
Jialin Cheng ◽  
Yeling Yun ◽  
Jingjing Wang ◽  
Jiaxin Rui ◽  
Shun Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Density Functional ◽  
Covalent Bond ◽  
First Principle ◽  
Compression Tests ◽  
Solid Solution Strengthening ◽  
First Principle Calculations ◽  
Fine Grain ◽  
Fine Grain Strengthening

Through the first-principle calculations based on density functional theory and experimental investigation, the structural stability elastic properties and mechanical properties of Ti2Cu and Ti18Cu5Nb1 intermetallics were studied. The first-principle calculations showed that the ratio of bulk modulus to shear modulus (B/G) and Poisson’s ratio (ν) of Ti2Cu and Ti18Cu5Nb1 intermetallics were 2.03, 0.288, and 2.22, 0.304, respectively, indicating that the two intermetallics were ductile. This was confirmed by the compression tests, which showed that the plastic strain of both intermetallics was beyond 25%. In addition, the yield strength increased from the 416 to 710 MPa with the addition of Nb. The increase in strength is the result of three factors, namely covalent bond tendency, fine grain strengthening, and solid solution strengthening. This finding gives clues to design novel intermetallics with excellent mechanical properties by first-principle calculations and alloying.

Vacancy-induced elastic properties and hardness of CrB4: A DFT calculation

2017 ◽  
Vol 31 (13) ◽  
pp. 1750096 ◽  
Author(s):  
Yong Pan ◽  
Song Chen ◽  
Yuanhua Lin
Keyword(s):  
Mechanical Properties ◽  
Dft Calculation ◽  
Covalent Bond ◽  
Elastic Stiffness ◽  
First Principle ◽  
Triangular Pyramid ◽  
First Principle Calculations ◽  
3D Network ◽  
Metal Borides ◽  
The Relationship

Vacancy plays a crucial role in mechanical properties of transition metal borides (TMBs). However, the influence of vacancy on hardness of TMBs is unknown. In this paper, the relationship between boron vacancy and mechanical properties of CrB4 is investigated by first-principle calculations. Two different vacancies including boron monovacancy (MV) and boron bivacancy (BV) are considered. We find that CrB4 with boron MV is more stable than that of boron BV. The removed atom weakens the deformation resistances, and reduces the elastic stiffness and hardness. The calculated shear modulus, Young’s modulus and theoretical hardness of boron MV are larger than that of boron BV. The reason is that the removed atom weakens the localized hybridization between B and B atoms, and damages the 3D-network B–B covalent bond. However, the bulk modulus of B[Formula: see text] is slightly larger than that of perfect CrB4. This reason is attributed to the formation of triangular pyramid bonding in B[Formula: see text] vacancy.

Covalent Bond Cluster Effects and Phase Transitions in Superconductor Mg1-xAlxB2 Compounds

2011 ◽  
Vol 55-57 ◽  
pp. 950-954
Author(s):  
Yan Bao ◽  
Yuan Zhao ◽  
Ni Zhu
Keyword(s):  
Phase Transitions ◽  
Band Structure ◽  
Covalent Bond ◽  
Doping Effect ◽  
Experimental Measurements ◽  
First Principle ◽  
Density Of State ◽  
First Principle Calculations ◽  
Densities Of States ◽  
Theoretical Predictions

First-principle calculations were performed for the study of the superconductor MgB2and AlB2. The doping effect of compound Mg1-xAlxB2was analyzed by supercell method. Band structure, electronic bands structure, total and partial densities of states were calculated and analyzed in detail. Covalent bond effects (CBC) appeared in the electronic bands structure when doping Al to MgB2. It is found that this CBC effects on Mg1-xAlxB2samples have prominent relations to superconductivity. The study of the density of state indicates that the superconductivity decreases with the increase of compound Al. In particular, there exists the transition of superconductor to non-superconductor with the change of x. The theoretical predictions agreed well with experimental measurements.

scholarly journals The electronic structure and optical properties of Ca3(Mn1−xTix)2O7from first-principle calculations

2019 ◽  
Vol 09 (01) ◽  
pp. 1950007
Author(s):  
Fengqi Wang ◽  
Wei Cai ◽  
Chunlin Fu ◽  
Rongli Gao ◽  
Gang Chen ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Band Gap ◽  
Population Analysis ◽  
Covalent Bond ◽  
Index Formula ◽  
First Principle ◽  
Mulliken Population ◽  
First Principle Calculations ◽  
Text Content

The electronic structure and optical properties of Ca3(Mn[Formula: see text]Ti[Formula: see text]O7 ([Formula: see text], 1/8, 2/8, 3/8, 4/8) were studied by first-principle calculations within the generalized gradient approximation approaches (GGA). The lattice constants of Ca3(Mn[Formula: see text]Ti[Formula: see text]O7 increase with the increase of Ti[Formula: see text] content caused by the substitution of Ti[Formula: see text] with larger ionic radius for Mn[Formula: see text]. Ca3(Mn[Formula: see text]Ti[Formula: see text]O7 is a direct band gap semiconductor, and the band gap ([Formula: see text]) increases with the increase of Ti[Formula: see text] content. From the density of states, the introduction of Ti-3[Formula: see text] states can weaken the effects of Mn-3[Formula: see text] states on the bottom of conduction band and has little influence on O-2[Formula: see text] states on the top of valence band. The introduction of nonmagnetic Ti[Formula: see text] ions can weaken the magnetism of Ca3(Mn[Formula: see text]Ti[Formula: see text]O7. According to the Mulliken population analysis, it is found that the introduction of Ti[Formula: see text] enhances the electronic accepting capacity of oxygen ions and enhances the electronic losing capacity of manganese ions. The bond strength of Ti–O covalent bond is stronger than that of Mn–O covalent bond. Furthermore, the optical properties of Ca3(Mn[Formula: see text]Ti[Formula: see text]O7 was calculated. As Ti[Formula: see text] content increases, the absorption edge of Ca3(Mn[Formula: see text]Ti[Formula: see text]O7 has a blue shift, the static refractive index [Formula: see text] decreases, the static dielectric constant [Formula: see text](0) decreases, the position of loss peak moves to higher energy.

AB-INITIO STUDY OF THE STRUCTURE OF Pd(110)-c(4×2)-BENZENE

1999 ◽  
Vol 06 (05) ◽  
pp. 903-906
Author(s):  
FABIO FAVOT ◽  
ANDREA DAL CORSO ◽  
ALFONSO BALDERESCHI
Keyword(s):  
Ab Initio ◽  
Adsorbed Molecule ◽  
Benzene Molecule ◽  
Planar Geometry ◽  
First Principle ◽  
Ab Initio Study ◽  
Substrate Interactions ◽  
Bond Lengths ◽  
First Principle Calculations

From first principle calculations we have determined the structure of the Pd(110)-c(4×2)-benzene system for three azimuthally different orientations of the benzene molecule (two with C2v and one with C2 symmetry). For all cases, in the relaxed structure the benzene molecule loses its planar geometry since the C–H bonds appreciably bend upwards, the carbon hexagon loses planar geometry too and exhibits inequivalent C–C bond lengths, and the substrate is slightly buckled. We discuss the calculated geometries in terms of benzene–substrate interactions and predict a C2 symmetry of the adsorbed molecule.

scholarly journals Analogous Diamondene Nanotube Structure Prediction Based on Molecular Dynamics and First-Principle Calculations

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 846
Author(s):  
Xin Zhou ◽  
Haifang Cai ◽  
Chunwei Hu ◽  
Jiao Shi ◽  
Zongli Li ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Structure Prediction ◽  
Gaussian Function ◽  
Covalent Bond ◽  
Outer Tube ◽  
First Principle ◽  
Change Rate ◽  
Type Iii ◽  
First Principle Calculations ◽  
The Ideal

A concentric twin tube (CTT) can be built by placing a carbon nanotube (CNT) in another identical CNT. Different from diamondene nanotubes, a stable CTT has no inter-shell covalent bond. As a prestressed double-walled nanotube, CTT has a lower structural stability at a finite temperature. According to the molecular dynamics and first-principle calculations, (a) CTTs have three types of relaxed configurations. In a type III CTT, the inner tube buckles to produce a V-shaped cross-section, and the outer tube may be convex or concave. (b) The minimal radii of relaxed zigzag and armchair CTTs with concave outer tubes were found. (c) After relaxation, the circumferences and areas of the two tubes in a type III CTT are different from those of the corresponding ideal CNT. The area change rate (A-CR) and circumference change rate (C-CR) of the outer tube are the first-order Gaussian function of the radius of the ideal CNT (which forms the CTT), and tends to be 73.3% of A-CR or 95.3% of C-CR, respectively. For the inner tube of a CTT, the A-CR is between 29.3% and 37.0%, and the C-CR is close to 95.8%. (d) The temperature slightly influences the findings given above.

Structural Stability and Electronic Properties of Fe-Doped B13C2: First-Principles Investigation

2013 ◽  
Vol 652-654 ◽  
pp. 344-347
Author(s):  
Yi Wei Qin ◽  
Sen Kai Lu
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Electronic Properties ◽  
First Principles ◽  
Structural Unit ◽  
Covalent Bond ◽  
Structure Stability ◽  
First Principle ◽  
First Principle Calculations ◽  
Pseudo Potential

Structure stability and electronic properties of Fe-doped boron carbides (B13C2) were studied using the first principle calculations based on plane wave pseudo-potential theory. The calculated results showed that the Fe-doped boron carbide representative stable structural is Fe substituting C atom on the end of chain C-B-C. The band structure and density of states (DOS) indicated that the coexistence of [C-B-Fe] ε+-[B11C] ε- structural unit made electrical conductivity increased. As the covalent bond of Fe-B was weaker than those of B-B and B-C, the thermal conductivity decreased for Fe-doped B13C2, thermoelectric property of Fe-doped boron carbides has been improved.

scholarly journals A First-Principle Study of Monolayer Transition Metal Carbon Trichalcogenides

2021 ◽  
Author(s):  
Muhammad Yar Khan ◽  
Yan Liu ◽  
Tao Wang ◽  
Hu Long ◽  
Miaogen Chen ◽  
...  
Keyword(s):  
Phonon Dispersion ◽  
Magnetic Ordering ◽  
Dimensional Structure ◽  
First Principle ◽  
Two Dimensional ◽  
Biaxial Strain ◽  
Half Metallic ◽  
First Principle Calculations ◽  
Potential Applications ◽  
External Strain

AbstractMonolayer MnCX3 metal–carbon trichalcogenides have been investigated by using the first-principle calculations. The compounds show half-metallic ferromagnetic characters. Our results reveal that their electronic and magnetic properties can be altered by applying uniaxial or biaxial strain. By tuning the strength of the external strain, the electronic bandgap and magnetic ordering of the compounds change and result in a phase transition from the half-metallic to the semiconducting phase. Furthermore, the vibrational and thermodynamic stability of the two-dimensional structure has been verified by calculating the phonon dispersion and molecular dynamics. Our study paves guidance for the potential applications of these two mono-layers in the future for spintronics and straintronics devices.

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