scholarly journals Structure-Property Relationships of 2D Ga/In Chalcogenides

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2188
Author(s):  
Pingping Jiang ◽  
Pascal Boulet ◽  
Marie-Christine Record
Keyword(s):  
Density Functional ◽  
Lattice Mismatch ◽  
Decisive Role ◽  
Interatomic Interaction ◽  
Structure Property ◽  
Functional Theory ◽  
Structure Property Relationships ◽  
Structure Property Relationship ◽  
Maximum Conversion Efficiency

Two-dimensional MX (M = Ga, In; X = S, Se, Te) homo- and heterostructures are of interest in electronics and optoelectronics. Structural, electronic and optical properties of bulk and layered MX and GaX/InX heterostructures have been investigated comprehensively using density functional theory (DFT) calculations. Based on the quantum theory of atoms in molecules, topological analyses of bond degree (BD), bond length (BL) and bond angle (BA) have been detailed for interpreting interatomic interactions, hence the structure–property relationship. The X–X BD correlates linearly with the ratio of local potential and kinetic energy, and decreases as X goes from S to Te. For van der Waals (vdW) homo- and heterostructures of GaX and InX, a cubic relationship between microscopic interatomic interaction and macroscopic electromagnetic behavior has been established firstly relating to weighted absolute BD summation and static dielectric constant. A decisive role of vdW interaction in layer-dependent properties has been identified. The GaX/InX heterostructures have bandgaps in the range 0.23–1.49 eV, absorption coefficients over 10−5 cm−1 and maximum conversion efficiency over 27%. Under strain, discordant BD evolutions are responsible for the exclusively distributed electrons and holes in sublayers of GaX/InX. Meanwhile, the interlayer BA adjustment with lattice mismatch explains the constraint-free lattice of the vdW heterostructure.

scholarly journals Structure–Property Relationships in Transition Metal Dichalcogenide Bilayers under Biaxial Strains

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2639
Author(s):  
Pingping Jiang ◽  
Pascal Boulet ◽  
Marie-Christine Record
Keyword(s):  
Density Functional ◽  
Compressive Strain ◽  
Bond Critical Point ◽  
Transition Metal Dichalcogenide ◽  
Structure Property ◽  
Photovoltaic Properties ◽  
Functional Theory ◽  
Leading Role ◽  
Structure Property Relationships

This paper reports a Density Functional Theory (DFT) investigation of the electron density and optoelectronic properties of two-dimensional (2D) MX2 (M = Mo, W and X = S, Se, Te) subjected to biaxial strains. Upon strains ranging from −4% (compressive strain) to +4% (tensile strain), MX2 bilayers keep the same bandgap type but undergo a non-symmetrical evolution of bandgap energies and corresponding effective masses of charge carriers (m*). Despite a consistency regarding the electronic properties of Mo- and WX2 for a given X, the strain-induced bandgap shrinkage and m* lowering are strong enough to alter the strain-free sequence MTe2, MSe2, MS2, thus tailoring the photovoltaic properties, which are found to be direction dependent. Based on the quantum theory of atoms in molecules, the bond degree (BD) at the bond critical points was determined. Under strain, the X-X BD decreases linearly as X atomic number increases. However, the kinetic energy per electron G/ρ at the bond critical point is independent of strains with the lowest values for X = Te, which can be related to the highest polarizability evidenced from the dielectric properties. A cubic relationship between the absolute BD summation of M-X and X-X bonds and the static relative permittivity was observed. The dominant position of X-X bond participating in this cubic relationship in the absence of strain was substantially reinforced in the presence of strain, yielding the leading role of the X-X bond instead of the M-X one in the photovoltaic response of 2D MX2 material.

scholarly journals Voltammetric and theoretical studies of electrochemical behavior of cephalosporins at the mercury electrode

2015 ◽  
Vol 80 (8) ◽  
pp. 1035-1049 ◽  
Author(s):  
Katarina Nikolic ◽  
Mara Aleksic ◽  
Vera Kapetanovic ◽  
Danica Agbaba
Keyword(s):  
Density Functional ◽  
Mercury Electrode ◽  
Differential Pulse ◽  
Structure Property ◽  
Qspr Model ◽  
Functional Theory ◽  
Partial Charges ◽  
The Density Functional Theory ◽  
Structure Property Relationship ◽  
Qspr Study

Study of the adsorption and electroreduction behavior of cefpodoxime proxetil, cefotaxime, desacetylcefotaxime, cefetamet, ceftriaxone, ceftazidime, and cefuroxime axetile at the mercury electrode surface has been performed using Cyclic (CV), Differential Pulse (DPV), and Adsorptive Stripping Differential Pulse Voltammetry (AdSDPV). The Quantitative Structure Property Relationship (QSPR) study of the seven cephalosporins adsorption at the mercury electrode has been based on the density functional theory DFT-B3LYP/6-31G (d,p) calculations of molecular orbitals, partial charges and electron densities of analytes. The DFT-parameters and QSPR model explain well the process of adsorption of the examined cephalosporins. QSPR study defined that cefalosporins with lower charge of sulphur in the thiazine moiety, lower electron density on the nitrogen atom of the N-O bond, higher number of hydrogen bond accepting groups, and higher principal moment of inertia should express high adsorption on the mercury electrode.

scholarly journals Electron Density and Its Relation with Electronic and Optical Properties in 2D Mo/W Dichalcogenides

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2221
Author(s):  
Pingping Jiang ◽  
Marie-Christine Record ◽  
Pascal Boulet
Keyword(s):  
Optical Properties ◽  
Lattice Mismatch ◽  
Compressive Strain ◽  
Interatomic Interaction ◽  
Structure Property ◽  
Electronic And Optical Properties ◽  
Cubic Equation ◽  
Structure Property Relationships ◽  
Stacking Order ◽  
Structures And Properties

Two-dimensional MX2 (M = Mo, W; X = S, Se, Te) homo- and heterostructures have attracted extensive attention in electronics and optoelectronics due to their unique structures and properties. In this work, the layer-dependent electronic and optical properties have been studied by varying layer thickness and stacking order. Based on the quantum theory of atoms in molecules, topological analyses on interatomic interactions of layered MX2 and WX2/MoX2, including bond degree (BD), bond length (BL), and bond angle (BA), have been detailed to probe structure-property relationships. Results show that M-X and X-X bonds are strengthened and weakened in layered MX2 compared to the counterparts in bulks. X-X and M-Se/Te are weakened at compressive strain while strengthened at tensile strain and are more responsive to the former than the latter. Discordant BD variation of individual parts of WX2/MoX2 accounts for exclusively distributed electrons and holes, yielding type-II band offsets. X-X BL correlates positively to binding energy (Eb), while X-X BA correlates negatively to lattice mismatch (lm). The resulting interlayer distance limitation evidences constraint-free lattice of vdW structure. Finally, the connection between microscopic interatomic interaction and macroscopic electromagnetic behavior has been quantified firstly by a cubic equation relating to weighted BD summation and static dielectric constant.

STABLE STRUCTURES AND CHARACTERISTIC VIBRATIONAL SPECTRA OF TinOm(n = 2–4; m = 1–2n) CLUSTERS

2013 ◽  
Vol 12 (01) ◽  
pp. 1250094 ◽  
Author(s):  
HONGBO DU ◽  
YU JIA ◽  
RUI-QIN ZHANG
Keyword(s):  
Density Functional Theory ◽  
Raman Spectrum ◽  
Density Functional ◽  
Structure Property ◽  
Functional Theory ◽  
Experimental Identification ◽  
Structure Property Relationships ◽  
Method Of Density Functional ◽  
Ir And Raman ◽  
Stable Structures

The energetically favorable structures and characteristic infrared (IR) and Raman peaks of Ti n O m(n = 2–4, m ≤ 2n) clusters are obtained in this work using a B3LYP/6-311G(d) method of density functional theory (DFT). The structures with m < 2n compose of Ti atoms of lower numbers of coordination with O atoms, providing many dangling bonds which considerably enhance the reactivity compared with its bulk counterpart. Two- and three-coordinated O atoms present for m/n ≤ 1.5, whereas two- and also single-coordinated O atoms are found for m/n > 1.5. The Ti n O m(n = 2–4, m < 2n) clusters show strong IR peaks in the range of 600–1100 cm-1 and strong Raman peaks in the region of 300–800 cm-1, whereas both the IR and Raman spectrum peaks of the Ti n O m(n = 2–4, m = 2n) clusters are in the region of 700–1100 cm-1. The main Raman peak of the Ti n O m(m ≠ 2n) clusters is at a frequency considerably lower than that of the IR spectrum. Our results can help understand the structure-property relationships of the Ti n O m clusters and provide their characteristic spectroscope features for further experimental identification.

scholarly journals The phase stability network of all inorganic materials

2020 ◽  
Vol 6 (9) ◽  
pp. eaay5606 ◽  
Author(s):  
Vinay I. Hegde ◽  
Muratahan Aykol ◽  
Scott Kirklin ◽  
Chris Wolverton
Keyword(s):  
Phase Stability ◽  
Density Functional ◽  
Materials Science ◽  
Inorganic Materials ◽  
Structure Property ◽  
Two Phase ◽  
Functional Theory ◽  
Structure Property Relationships ◽  
Complementary Approach ◽  
Tie Line

One of the holy grails of materials science, unlocking structure-property relationships, has largely been pursued via bottom-up investigations of how the arrangement of atoms and interatomic bonding in a material determine its macroscopic behavior. Here, we consider a complementary approach, a top-down study of the organizational structure of networks of materials, based on the interaction between materials themselves. We unravel the complete “phase stability network of all inorganic materials” as a densely connected complex network of 21,000 thermodynamically stable compounds (nodes) interlinked by 41 million tie line (edges) defining their two-phase equilibria, as computed by high-throughput density functional theory. Analyzing the topology of this network of materials has the potential to uncover previously unidentified characteristics inaccessible from traditional atoms-to-materials paradigms. Using the connectivity of nodes in the phase stability network, we derive a rational, data-driven metric for material reactivity, the “nobility index,” and quantitatively identify the noblest materials in nature.

Computational study on thermally activated delayed fluorescence of donor–linker–acceptor network molecules

RSC Advances ◽  
2016 ◽  
Vol 6 (43) ◽  
pp. 37203-37211 ◽  
Author(s):  
Talapunur Vikramaditya ◽  
Mukka Saisudhakar ◽  
Kanakamma Sumithra
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Organic Molecules ◽  
Computational Study ◽  
Delayed Fluorescence ◽  
Structure Property ◽  
Functional Theory ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Structure Property Relationships

Using density functional theory we have investigated the structure–property relationships of organic molecules with a donor–linker–acceptor (DLA) framework, which can be used as precursors of OLED materials.

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