Carrier mobility of one-dimensional vanadium selenide (V2Se9) monolayer and nanoribbon systems: DFT study

2021 ◽  
Author(s):  
Junho Lee ◽  
You Kyoung Chung ◽  
Dongchul Sung ◽  
ByungJoo Jeong ◽  
Seongbae Oh ◽  
...  
Keyword(s):  
Electron Mobility ◽  
Carrier Mobility ◽  
Density Functional ◽  
High Electron ◽  
Deformation Potential ◽  
Functional Theory ◽  
One Dimensional ◽  
Computational Analyses ◽  
Vanadium Selenide ◽  
Deformation Potential Theory

Abstract Vanadium selenide (V2Se9) is a true one-dimensional (1D) crystal composed of atomic nanochains bonded by van der Waals (vdW) interactions. Recent experiments revealed the mechanical exfoliation of newly synthesized V2Se9. In this study, we predicted the electronic and transport properties of V2Se9 through computational analyses. We calculated the intrinsic carrier mobility of V2Se9 monolayers (MLs) and nanoribbons (NRs) using density functional theory and deformation potential theory. We found that the electron mobility of the two-dimensional (2D) (010)-plane ML of V2Se9 is highly anisotropic, reaching μ_(2D,z)^e=1327 cm2 V−1 s−1 across the chain direction. The electron mobility of 1D NR systems in a (010)-plane ML of V2Se9 along the chain direction continuously increased as the thickness increased from 1-chain to 4-chain NR (width below 3 nm). Interestingly, the electron mobility of 1D 4-chain NR along the chain direction (μ_(1D,x)^e=775 cm2 V−1 s−1) was higher than that of a 2D (010)-plane ML (μ_(2D,x)^e=567 cm2 V−1 s−1). These results demonstrate the potential of vdW-1D crystal V2Se9 as a new nanomaterial for ultranarrow (sub-3-nm width) optoelectronic devices with high electron mobility.

Novel Janus group III chalcogenide monolayers Al2XY2 (X/Y= S, Se, Te): First-principles insight onto the structural, electronic, and transport properties

2021 ◽  
Author(s):  
Tuan V. Vu ◽  
Nguyen N. Hieu
Keyword(s):  
Transport Properties ◽  
Electron Mobility ◽  
Density Functional ◽  
High Electron ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Group Iii ◽  
The Density Functional Theory ◽  
First Time ◽  
Two Sides

Abstract Motivated by the recent successful synthesis of 2D quintuple-layer atomic materials, for the first time, we design and investigate the electronic and transport properties of Janus Al$_2XY_2$ ($X/Y =$ S, Se, Te; $X \neq Y$) monolayers by using the density functional theory. Our calculations demonstrate that most of the models of Al$_2XY_2$ (except for Al$_2$STe$_2$ monolayer) are dynamically and mechanically stable. By using the hybrid functional, all models of Al$_2XY_2$ are semiconductors with an indirect bandgap. Meanwhile, Al$_2$TeS$_2$ monolayer is found to be metal at the PBE level. Due to the vertical asymmetry structure, an intrinsic built-in electric field exists in the Al$_2XY_2$ and leads to a difference in the vacuum levels between the two sides of the monolayers. Carrier mobilities of Al$_2XY_2$ monolayers are high directional anisotropic due to the anisotropy of their deformation potential constant. Al$_2XY_2$ monolayers exhibit high electron mobility, particularly, the electron mobility of Al$_2$SeS$_2$ exceeds $1\times 10^4$~cm$^2$/Vs, suggesting that they are suitable for applications in nanometer sized electronic devices.

scholarly journals Quasi-1D XY antiferromagnet Sr2Ni(SeO3)2Cl2 at Sakai-Takahashi phase diagram

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. S. Kozlyakova ◽  
A. V. Moskin ◽  
P. S. Berdonosov ◽  
V. V. Gapontsev ◽  
S. V. Streltsov ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Long Range ◽  
Density Functional ◽  
Uniaxial Anisotropy ◽  
Exchange Interactions ◽  
Spin Liquid ◽  
Functional Theory ◽  
One Dimensional ◽  
Ordered Phases ◽  
Experimental Findings

AbstractUniform quasi-one-dimensional integer spin compounds are of interest as a potential realization of the Haldane conjecture of a gapped spin liquid. This phase, however, has to compete with magnetic anisotropy and long-range ordered phases, the implementation of which depends on the ratio of interchain J′ and intrachain J exchange interactions and both uniaxial D and rhombic E single-ion anisotropies. Strontium nickel selenite chloride, Sr2Ni(SeO3)2Cl2, is a spin-1 chain system which passes through a correlations regime at Tmax ~ 12 K to long-range order at TN = 6 K. Under external magnetic field it experiences the sequence of spin-flop at Bc1 = 9.0 T and spin-flip transitions Bc2 = 23.7 T prior to full saturation at Bsat = 31.0 T. Density functional theory provides values of the main exchange interactions and uniaxial anisotropy which corroborate the experimental findings. The values of J′/J = 0.083 and D/J = 0.357 place this compound into a hitherto unoccupied sector of the Sakai-Takahashi phase diagram.

scholarly journals Isolation of a Bimetallic Cobalt(III) Nitride and Examination of its Hydrogen Atom Abstraction Chemistry and Reactivity Towards H2

2020 ◽  
Author(s):  
Debabrata Sengupta ◽  
Christian Sandoval-Pauker ◽  
Emily Schueller ◽  
Angela M. Encerrado-Manriquez ◽  
Alejandro J. Metta-Magaña ◽  
...  
Keyword(s):  
Hydrogen Atom ◽  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Atom Abstraction ◽  
Functional Theory ◽  
Kinetic Rate ◽  
Rate Analysis ◽  
Stable Product ◽  
Activation Pathways ◽  
Computational Analyses

Room temperature photolysis of the bis(azide)cobaltate(II) complex [Na(THF)<sub>x</sub>][(<sup>ket</sup>guan)Co(N3)2] (<sup>ket</sup>guan = [(tBu2CN)C(NDipp)2]–, Dipp = 2,6-diisopropylphenyl) (3a) in THF cleanly forms the binuclear cobalt nitride [Na(THF)4{[(<sup>ket</sup>guan)Co(N3)]2(μ-N)}]<sub>n</sub> (1). Compound 1 represents the first example of an isolable, bimetallic cobalt nitride complex, and it has been fully characterized by spectroscopic, magnetic, and computational analyses. Density functional theory supports a CoIII=N=CoIII canonical form with significant π-bonding between the cobalt centers and the nitride atom. Unlike other Group 9 bridging nitride complexes, no radical character is detected at the bridging N-atom of 1. Indeed, 1 is unreactive towards weak C-H donors and even co-crystallizes with a molecule of cyclohexadiene (CHD) in its crystallographic unit cell to give 1·CHD as a room temperature stable product. Notably, addition of pyridine to 1 or photolyzed solutions of [(<sup>ket</sup>guan)Co(N3)(py)]<sub>2</sub> (4a) leads to destabilization via activation of the nitride unit, resulting in the mixed-valent Co(II)/(III) bridged imido species [(<sup>ket</sup>guan)Co]2(μ-NH)(μ-N3) (5) formed from intermolecular hydrogen atom abstraction (HAA) of strong C-H bonds (BDE ~ 100 kcal/mol). Kinetic rate analysis of the formation of 5 in the presence of C6H12 or C6D12 gives a KIE = 2.5±0.1, supportive of a HAA formation path-way. The reactivity of our system was further probed by photolyzing C6D6/py-d5 solutions of 4a under an H2 atmosphere (150 psi), which leads to the exclusive formation of the bis(imido)[(<sup>ket</sup>guan)Co(μ-NH)]2 (6) as a result of dihydrogen activa-tion. These results provide unique insights into the chemistry and electronic structure of late 3d-metal nitrides while providing entryway into C-H activation pathways.

Computational analyses of Fe-Chelation by thiofavipiravir

2021 ◽  
pp. 1-9
Author(s):  
Halimeh Rajabzadeh ◽  
Maryam Abbasi ◽  
Mostafa Tohoidian
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Living Systems ◽  
Functional Theory ◽  
Challenging Issue ◽  
The Density Functional Theory ◽  
Novel Coronavirus ◽  
Computational Analyses ◽  
Oxygen Atoms

Existence of iron (Fe) is important for cells of living systems; however, its level of magnitude for those patients infected by novel coronavirus disease (COVID-19) is still a challenging issue. Therefore, such mechanism of function was investigated in this work by assistance of thiofavipiravir (TFav) compounds generated by the well-known favipiravir (Fav) drug used for medication of COVID-19 patents. To this aim, sulfur-substitutions of oxygen atoms of Fav were done and the obtained parent structures were prepared for participating in Fe-chelation function. The results indicated that the modes were suitable for running such Fe-chelation processes, in which favorability and strength the models were ranged in this order: 1O2S-Fe >  1S2S-Fe >  1O2O-Fe >  1S2O-Fe. As a consequence, such idea of sulfur-substitution of Fav drug for more appropriate favorability of participating in Fe-chelation process was sensed by results of this work proposing 1O2S compound as the most favorable one for doing the function. Hence, information about capability of TFav compounds for participating in Fe-chelation processes were provided in this work regarding the challenging issue of Fe-chelation in medication of COVID-19 patients. All results of this work were obtained by performing computations using the density functional theory (DFT) approach

Pharmaceutical salts of emoxypine with dicarboxylic acids

2018 ◽  
Vol 74 (7) ◽  
pp. 797-806 ◽  
Author(s):  
Alex N. Manin ◽  
Alexander P. Voronin ◽  
Ksenia V. Drozd ◽  
Andrei V. Churakov ◽  
German L. Perlovich
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Dicarboxylic Acids ◽  
Lattice Energy ◽  
State Density ◽  
Functional Theory ◽  
One Dimensional ◽  
Fusion Enthalpy ◽  
Pharmaceutical Salts ◽  
Salt Forms

New salt forms of the antioxidant drug emoxypine (EMX, 2-ethyl-6-methylpyridin-3-ol) with pharmaceutically acceptable maleic (Mlt), malonic (Mln) and adipic (Adp) acids were obtained {emoxypinium maleate, C8H12NO+·C4H3O4 −, [EMX+Mlt], emoxypinium malonate, C8H12NO+·C3H3O4 −, [EMX+Mln], and emoxypinium adipate, C8H12NO+·C6H9O4 −, [EMX+Adp]} and their crystal structures determined. The molecular packing in the three EMX salts was studied by means of solid-state density functional theory (DFT), followed by QTAIMC (quantum theory of atoms in molecules and crystals) analysis. It was found that the major contribution to the packing energy comes from pyridine–carboxylate and hydroxy–carboxylate heterosynthons forming infinite one-dimensional ribbons, with [EMX+Adp] additionally stabilized by hydrogen-bonded C(9) chains of Adp− ions. The melting processes of the [EMX+Mlt] (1:1), [EMX+Mln] (1:1) and [EMX+Adp] (1:1) salts were studied and the fusion enthalpy was found to increase with the increase of the calculated lattice energy. The dissolution process of the EMX salts in buffer (pH 7.4) was also studied. It was found that the formation of binary crystals of EMX with dicarboxylic acids increases the EMX solubility by more than 30 times compared to its pure form.

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