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Junhao Chu - One of the best experts on this subject based on the ideXlab platform.
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manipulation of the large rashba spin splitting in polar two dimensional transition metal dichalcogenides
Physical Review B, 2017Co-Authors: Qunfang Yao, Jia Cai, Wenyi Tong, Shijing Gong, Jiqing Wang, Xiangang Wan, Chungang Duan, Junhao ChuAbstract:Transition metal dichalcogenide (TMD) monolayers MXY (M=Mo, W, X(not equal to)Y=S, Se, Te) are two-dimensional polar semiconductors. Setting WSeTe monolayer as an example and using density functional theory calculations, we investigate the manipulation of Rashba spin orbit coupling (SOC) in the MXY monolayer. It is found that the intrinsic out-of-plane electric field due to the mirror symmetry breaking induces the large Rashba spin splitting around the Gamma point, which, however, can be easily tuned by applying the in-plane biaxial strain. Through a relatively small strain (from -2% to 2%), a large tunability (from around -50% to 50%) of Rashba SOC can be obtained due to the modified Orbital Overlap, which can in turn modulate the intrinsic electric field. The Orbital selective external potential method further confirms the significance of the Orbital Overlap between W-dz2 and Se-pz in Rashba SOC. In addition, we also explore the influence of the external electric field on Rashba SOC in the WSeTe monolayer, which is less effective than strain. The large Rashba spin splitting, together with the valley spin splitting in MXY monolayers may make a special contribution to semiconductor spintronics and valleytronics.
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manipulation of the large rashba spin splitting in polar two dimensional transition metal dichalcogenides
Physical Review B, 2017Co-Authors: Qunfang Yao, Jia Cai, Wenyi Tong, Shijing Gong, Jiqing Wang, Xiangang Wan, Chungang Duan, Junhao ChuAbstract:Transition-metal dichalcogenide (TMD) monolayers $MXY\phantom{\rule{0.16em}{0ex}}(M=\mathrm{Mo},\phantom{\rule{0.16em}{0ex}}\mathrm{W};X\phantom{\rule{0.16em}{0ex}}\ensuremath{\ne}\phantom{\rule{0.16em}{0ex}}Y=\mathrm{S},\phantom{\rule{0.16em}{0ex}}\mathrm{Se},\phantom{\rule{0.16em}{0ex}}\mathrm{Te})$ are two-dimensional polar semiconductors. Setting the WSeTe monolayer as an example and using density functional theory calculations, we investigate the manipulation of Rashba spin-orbit coupling (SOC) in the MXY monolayer. It is found that the intrinsic out-of-plane electric field due to the mirror symmetry breaking induces the large Rashba spin splitting around the $\mathrm{\ensuremath{\Gamma}}$ point, which, however, can be easily tuned by applying the in-plane biaxial strain. Through a relatively small strain (from $\ensuremath{-}2%$ to 2%), a large tunability (from around $\ensuremath{-}50%$ to 50%) of Rashba SOC can be obtained due to the modified Orbital Overlap, which can in turn modulate the intrinsic electric field. The Orbital selective external potential method further confirms the significance of the Orbital Overlap between $\mathrm{W}\text{\ensuremath{-}}{d}_{{z}^{2}}$ and $\mathrm{Se}\text{\ensuremath{-}}{p}_{z}$ in Rashba SOC. In addition, we also explore the influence of the external electric field on Rashba SOC in the WSeTe monolayer, which is less effective than strain. By calculating the electric-field-induced Rashba SOC in all six $M{X}_{2}$ monolayers, the rule of the electric-field influence on Rashba SOC in TMD monolayers is demonstrated. The large Rashba spin splitting, together with the valley spin splitting in MXY monolayers, may make a special contribution to semiconductor spintronics and valleytronics.
Benjamin G Janesko - One of the best experts on this subject based on the ideXlab platform.
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Extending the Marcus μ-Scale of Solvent Softness Using Conceptual Density Functional Theory and the Orbital Overlap Distance: Method and Application to Ionic Liquids
Journal of Solution Chemistry, 2020Co-Authors: Arshad Mehmood, Benjamin G JaneskoAbstract:The chemical hardness of a solvent can play a decisive role in solubility and reactivity in solution. Several empirical scales quantifying solvent softness have been proposed. We explore whether computed properties of solvent molecules can reproduce these experimental scales. Our “Orbital Overlap distance” quantifying the size of Orbitals at a molecule’s surface effectively reproduces the Marcus μ -scale of solvent softness. The Orbital Overlap distance predicts that the surface of chemically hard solvent molecules is dominated by compact Orbitals possessing a small Orbital Overlap distance. In contrast, the surface of chemically soft solvent molecules has a larger contribution from diffuse Orbitals and a larger Orbital Overlap distance. Other conceptual density functional theory descriptors, including the global hardness and electronegativity, can also reproduce the Marcus scale. We further introduce a “solvent versatility” RMSD D _surf scale quantifying variations in the surface Orbital Overlap distance. “Good” solvents such as DMSO, which combine chemically “hard” and “soft” sites within a single molecule, possess a large RMSD D _surf. We conclude by applying this approach to predict the Marcus μ -parameters for widely-used ionic liquids and ionic liquid–cosolvent systems.
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an Orbital Overlap complement to ligand and binding site electrostatic potential maps
Journal of Chemical Information and Modeling, 2018Co-Authors: Arshad Mehmood, Stephanie I Jones, Peng Tao, Benjamin G JaneskoAbstract:Orbitals and Orbital Overlap are important concepts in chemistry but are seldom incorporated into medicinal chemistry analyses of drug–target interactions. Our Orbital Overlap distance D(r) quantifies the size of the “test Orbital” that best Overlaps with a system’s computed Orbitals at point r. The Overlap distance provides information about all of the occupied Orbitals across a molecule, extending frontier Orbital (Fukui) analysis and complementing widely used maps of the surface electrostatic potential. We present the first tests of the Overlap distance for problems in medicinal chemistry. The Overlap distance quantifies the different coordination chemistries of pairs of metal cations possessing similar charges and ionic radii. Combining the Overlap distance and electrostatic potential provides a rich picture of the binding sites for chemically “hard” versus “soft” cations in formylglycine-generating enzyme and extends frontier Orbital analysis in quantifying the chemistry of promiscuous binders. We co...
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An Orbital-Overlap Complement to Ligand and Binding Site Electrostatic Potential Maps
2018Co-Authors: Arshad Mehmood, Stephanie I Jones, Peng Tao, Benjamin G JaneskoAbstract:Orbitals and Orbital Overlap are important concepts in chemistry but are seldom incorporated into medicinal chemistry analyses of drug–target interactions. Our Orbital Overlap distance D(r) quantifies the size of the “test Orbital” that best Overlaps with a system’s computed Orbitals at point r. The Overlap distance provides information about all of the occupied Orbitals across a molecule, extending frontier Orbital (Fukui) analysis and complementing widely used maps of the surface electrostatic potential. We present the first tests of the Overlap distance for problems in medicinal chemistry. The Overlap distance quantifies the different coordination chemistries of pairs of metal cations possessing similar charges and ionic radii. Combining the Overlap distance and electrostatic potential provides a rich picture of the binding sites for chemically “hard” versus “soft” cations in formylglycine-generating enzyme and extends frontier Orbital analysis in quantifying the chemistry of promiscuous binders. We conclude by showing how the electrostatic potential and Overlap distance combine to give a novel and experimentally testable prediction for improving the in vivo activity of centromere-associated protein E inhibitors. The results motivate including the Overlap distance alongside electrostatic potential maps in medicinal chemistry
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an Orbital Overlap complement to atomic partial charge
Angewandte Chemie, 2017Co-Authors: Arshad Mehmood, Benjamin G JaneskoAbstract:Atomic partial charges are widely used to predict reactivity. Partial charge alone is often insufficient: the carbons of benzene and cyclobutadiene, or those of diamond, graphene, and C60, possess nearly identical partial charges and very different reactivities. Our atomic Overlap distance complements computed partial charges by measuring the size of Orbital lobes that best Overlap with the wavefunction around an atom. Compact, chemically stable atoms tend to have Overlap distances smaller than chemically soft, unstable atoms. We show here how combining atomic charges and Overlap distances captures trends in aromaticity, nucleophilicity, allotrope stability, and substituent effects. Applications to recent experiments in organic chemistry (counterintuitive Lewis base stabilization of alkenyl anions in anionic cyclization) and nanomaterials chemistry (facile doping of the central atom in Au7 hexagons) illustrate this combination's predictive power.
Jan Reedijk - One of the best experts on this subject based on the ideXlab platform.
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synthesis and crystal structure of 1 1 2 2 tetramethylguanidinium ni dmit 2 2 and hexamethylguanidinium ni dmit 2 2 dmit 1 3 dithiole 2 thione 4 5 dithiolate intermolecular Orbital Overlap integral calculations and electrical conductivities
Inorganica Chimica Acta, 1996Co-Authors: Yvonne S J Veldhuizen, Nora Veldman, Miles T Lakin, Anthony L Spek, Peter M Paulus, Christophe Faulmann, Jaap G Haasnoot, Wim J A Maaskant, Jan ReedijkAbstract:Abstract Electro-oxidation of a solution of [Bu4N][Ni(dmit)2] (dmit = C3S52− = 1,3-dithiole-2-thione-4,5-dithiolate) in the presence of a large excess of 1,1,2,2-tetramethylguanidinium chloride (Me4GuaCl) or hexamethylguanidinium iodide (Me6GuaI) yields black crystals of [Me4Gua][Ni(dmit)2]2 (1) and [Me6Gua][Ni(dmit)2]2 (2), respectively. The X-ray structures of 1 and 2 were determined in space group P 1 (No. 2) with for 1 a = 5.924(3), b = 8.078(3), c = 18.088(6) A, α = 89.71(3), β = 83.74(3), γ = 76.12(3)°, V = 835.1(6) A 3 , Z = 1, R1 = 0.031, wR2 = 0.077 , and for 2 a = 6.0080(4), b = 8.2739(5), c = 18.1173(9) A, α = 91.235(5), β = 93.978(5), γ = 102.278(6)°, V = 877.28(9) A 3 , Z = 1, R1 = 0.027, wR2 = 0.069 . The anionic part of the structures is approximately the same. The slightly dimerized Ni(dmit)2 units form layers with a two-dimensional network of S…S interactions in the ab plane. For both compounds intermolecular Orbital Overlap integral calculations point towards a weak two-dimensional conduction pathway in the ab plane. Conductivity measurements indicate a room temperature value of 0.08 S cm−1 for 1 and 0.03 S cm−1 for 2. Both compounds behave as semiconductors in the temperature range 300-100 K with Ea = 0.15 and 0.10 eV for 1 and 2, respectively. Montgomery single-crystal measurements on compound 2 showed that the anisotropy in the bc plane is small.
Arshad Mehmood - One of the best experts on this subject based on the ideXlab platform.
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Extending the Marcus μ-Scale of Solvent Softness Using Conceptual Density Functional Theory and the Orbital Overlap Distance: Method and Application to Ionic Liquids
Journal of Solution Chemistry, 2020Co-Authors: Arshad Mehmood, Benjamin G JaneskoAbstract:The chemical hardness of a solvent can play a decisive role in solubility and reactivity in solution. Several empirical scales quantifying solvent softness have been proposed. We explore whether computed properties of solvent molecules can reproduce these experimental scales. Our “Orbital Overlap distance” quantifying the size of Orbitals at a molecule’s surface effectively reproduces the Marcus μ -scale of solvent softness. The Orbital Overlap distance predicts that the surface of chemically hard solvent molecules is dominated by compact Orbitals possessing a small Orbital Overlap distance. In contrast, the surface of chemically soft solvent molecules has a larger contribution from diffuse Orbitals and a larger Orbital Overlap distance. Other conceptual density functional theory descriptors, including the global hardness and electronegativity, can also reproduce the Marcus scale. We further introduce a “solvent versatility” RMSD D _surf scale quantifying variations in the surface Orbital Overlap distance. “Good” solvents such as DMSO, which combine chemically “hard” and “soft” sites within a single molecule, possess a large RMSD D _surf. We conclude by applying this approach to predict the Marcus μ -parameters for widely-used ionic liquids and ionic liquid–cosolvent systems.
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an Orbital Overlap complement to ligand and binding site electrostatic potential maps
Journal of Chemical Information and Modeling, 2018Co-Authors: Arshad Mehmood, Stephanie I Jones, Peng Tao, Benjamin G JaneskoAbstract:Orbitals and Orbital Overlap are important concepts in chemistry but are seldom incorporated into medicinal chemistry analyses of drug–target interactions. Our Orbital Overlap distance D(r) quantifies the size of the “test Orbital” that best Overlaps with a system’s computed Orbitals at point r. The Overlap distance provides information about all of the occupied Orbitals across a molecule, extending frontier Orbital (Fukui) analysis and complementing widely used maps of the surface electrostatic potential. We present the first tests of the Overlap distance for problems in medicinal chemistry. The Overlap distance quantifies the different coordination chemistries of pairs of metal cations possessing similar charges and ionic radii. Combining the Overlap distance and electrostatic potential provides a rich picture of the binding sites for chemically “hard” versus “soft” cations in formylglycine-generating enzyme and extends frontier Orbital analysis in quantifying the chemistry of promiscuous binders. We co...
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An Orbital-Overlap Complement to Ligand and Binding Site Electrostatic Potential Maps
2018Co-Authors: Arshad Mehmood, Stephanie I Jones, Peng Tao, Benjamin G JaneskoAbstract:Orbitals and Orbital Overlap are important concepts in chemistry but are seldom incorporated into medicinal chemistry analyses of drug–target interactions. Our Orbital Overlap distance D(r) quantifies the size of the “test Orbital” that best Overlaps with a system’s computed Orbitals at point r. The Overlap distance provides information about all of the occupied Orbitals across a molecule, extending frontier Orbital (Fukui) analysis and complementing widely used maps of the surface electrostatic potential. We present the first tests of the Overlap distance for problems in medicinal chemistry. The Overlap distance quantifies the different coordination chemistries of pairs of metal cations possessing similar charges and ionic radii. Combining the Overlap distance and electrostatic potential provides a rich picture of the binding sites for chemically “hard” versus “soft” cations in formylglycine-generating enzyme and extends frontier Orbital analysis in quantifying the chemistry of promiscuous binders. We conclude by showing how the electrostatic potential and Overlap distance combine to give a novel and experimentally testable prediction for improving the in vivo activity of centromere-associated protein E inhibitors. The results motivate including the Overlap distance alongside electrostatic potential maps in medicinal chemistry
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an Orbital Overlap complement to atomic partial charge
Angewandte Chemie, 2017Co-Authors: Arshad Mehmood, Benjamin G JaneskoAbstract:Atomic partial charges are widely used to predict reactivity. Partial charge alone is often insufficient: the carbons of benzene and cyclobutadiene, or those of diamond, graphene, and C60, possess nearly identical partial charges and very different reactivities. Our atomic Overlap distance complements computed partial charges by measuring the size of Orbital lobes that best Overlap with the wavefunction around an atom. Compact, chemically stable atoms tend to have Overlap distances smaller than chemically soft, unstable atoms. We show here how combining atomic charges and Overlap distances captures trends in aromaticity, nucleophilicity, allotrope stability, and substituent effects. Applications to recent experiments in organic chemistry (counterintuitive Lewis base stabilization of alkenyl anions in anionic cyclization) and nanomaterials chemistry (facile doping of the central atom in Au7 hexagons) illustrate this combination's predictive power.
Yvonne S J Veldhuizen - One of the best experts on this subject based on the ideXlab platform.
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synthesis and crystal structure of 1 1 2 2 tetramethylguanidinium ni dmit 2 2 and hexamethylguanidinium ni dmit 2 2 dmit 1 3 dithiole 2 thione 4 5 dithiolate intermolecular Orbital Overlap integral calculations and electrical conductivities
Inorganica Chimica Acta, 1996Co-Authors: Yvonne S J Veldhuizen, Nora Veldman, Miles T Lakin, Anthony L Spek, Peter M Paulus, Christophe Faulmann, Jaap G Haasnoot, Wim J A Maaskant, Jan ReedijkAbstract:Abstract Electro-oxidation of a solution of [Bu4N][Ni(dmit)2] (dmit = C3S52− = 1,3-dithiole-2-thione-4,5-dithiolate) in the presence of a large excess of 1,1,2,2-tetramethylguanidinium chloride (Me4GuaCl) or hexamethylguanidinium iodide (Me6GuaI) yields black crystals of [Me4Gua][Ni(dmit)2]2 (1) and [Me6Gua][Ni(dmit)2]2 (2), respectively. The X-ray structures of 1 and 2 were determined in space group P 1 (No. 2) with for 1 a = 5.924(3), b = 8.078(3), c = 18.088(6) A, α = 89.71(3), β = 83.74(3), γ = 76.12(3)°, V = 835.1(6) A 3 , Z = 1, R1 = 0.031, wR2 = 0.077 , and for 2 a = 6.0080(4), b = 8.2739(5), c = 18.1173(9) A, α = 91.235(5), β = 93.978(5), γ = 102.278(6)°, V = 877.28(9) A 3 , Z = 1, R1 = 0.027, wR2 = 0.069 . The anionic part of the structures is approximately the same. The slightly dimerized Ni(dmit)2 units form layers with a two-dimensional network of S…S interactions in the ab plane. For both compounds intermolecular Orbital Overlap integral calculations point towards a weak two-dimensional conduction pathway in the ab plane. Conductivity measurements indicate a room temperature value of 0.08 S cm−1 for 1 and 0.03 S cm−1 for 2. Both compounds behave as semiconductors in the temperature range 300-100 K with Ea = 0.15 and 0.10 eV for 1 and 2, respectively. Montgomery single-crystal measurements on compound 2 showed that the anisotropy in the bc plane is small.