scholarly journals Dimethyl sulfoxide as a strongly coordinating solvent: 3′,4′-dihydroxyflavone-Cu(II)-DMSO system case study

2020 ◽  
Vol 13 (2) ◽  
pp. 38-48
Author(s):  
Miriama Šimunková ◽  
Michal Malček
Keyword(s):  
Dimethyl Sulfoxide ◽  
Density Functional ◽  
Chemical Interaction ◽  
Mulliken Population ◽  
Spin Distribution ◽  
Functional Theory ◽  
Dmso System ◽  
The Density Functional Theory ◽  
Coordination Ability

Abstract Dimethyl sulfoxide (DMSO) is an aprotic organic solvent widely used in laboratory practice due to its ability to dissolve both polar and nonpolar compounds. However, DMSO is also commonly known as a strongly coordinating solvent, especially towards transition metal containing complexes. In this study, estimation of the coordination ability of DMSO towards the Cu(II) ion was attempted, employing a model system composed of 3′,4′-dihydroxyflavone-Cu(II) complex in the presence of explicit DMSO molecules, using the density functional theory (DFT). Nature of the Cu-DMSO chemical interaction (i.e. Cu-O bonding) was studied within the framework of quantum theory of atoms in molecules (QTAIM). Impact of DMSO coordination on the charge and spin distribution at Cu(II) ion was inspected using Mulliken population and QTAIM analysis.

First-Principles Study of Ag3Sn, AgZn3 and Ag5Zn8 Intermetallic Compounds

2021 ◽  
Vol 871 ◽  
pp. 254-263
Author(s):  
Zhan Cheng ◽  
Guan Xing Zhang ◽  
Wei Min Long ◽  
Svitlana Maksymova ◽  
Jian Xiu Liu
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Constant Density ◽  
Mulliken Population ◽  
Covalent Bonds ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Anisotropy Index ◽  
Ionic Bonds

The first-principles calculations by CASTEP program based on the density functional theory is applied to calculate the cohesive energy, enthalpy of formation, elastic constant, density of states and Mulliken population of Ag3Sn、AgZn3 and Ag5Zn8. Furthermore, the elastic properties, bonding characteristics, and intrinsic connections of different phases are investigated. The results show that Ag3Sn、AgZn3 and Ag5Zn8 have stability structural, plasticity characteristics and different degrees of elastic anisotropy; Ag3Sn is the most stable structural, has the strongest alloying ability and the best plasticity. AgZn3 is the most unstable structure, has the worst plasticity; The strength of Ag5Zn8 is strongest, AgZn3 has the weakest strength, the largest shear resistance, and the highest hardness. Ag5Zn8 has the maximum Anisotropy index and Ag3Sn has the minimum Anisotropy index. Ag3Sn、AgZn3 and Ag5Zn8 are all have covalent bonds and ionic bonds, the ionic bonds decrease in the order Ag3Sn>Ag5Zn8>AgZn3 and covalent bonds decreases in the order Ag5Zn8>Ag3Sn>AgZn3.

First Principles Study of Surface Properties for Silicon Carbide-Derived Structures

2012 ◽  
Vol 433-440 ◽  
pp. 306-312
Author(s):  
Hong Ge Liu ◽  
Rui Jun Zhang ◽  
Hong Yan Jin ◽  
Qiu Xiang Liu
Keyword(s):  
Silicon Carbide ◽  
Surface Properties ◽  
First Principles ◽  
Density Functional ◽  
Population Analysis ◽  
Mulliken Population ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Nanoporous Surface ◽  
Pseudo Potential

Using first-principles ultra-soft pseudo-potential approach of the plane wave based on the density functional theory (DFT), we investigated the surface properties for silicon carbide-derived structure (i.e. SiCDS). The calculated results show that, movement of C and Si atoms caused by Si removal results in surface structural changing, and a nanoporous surface feature can be observed on the SiCDS surfaces when more Si atoms are removed. The mulliken population analysis indicates that the Si removal leads to the stronger chemical bonds between C–Si and the formation of new stronger chemical bands between C–C. From the density of states, as the Si removal proportion increases, C2p becomes gradually dominant in the SiCDS surface state electrons. Moreover, the Si removal leads to evidently different band gaps, indicating that the conductivity for SiCDS surface structures can be adjusted through the Si removal.

scholarly journals On the Use of DFT+U to Describe the Electronic Structure of TiO2 Nanoparticles: (TiO2)35 as a Case Study

2020 ◽  
Author(s):  
Angel Morales ◽  
Stephen Rhatigan ◽  
Michael Nolan ◽  
Frances Illas
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Plane Waves ◽  
Basis Set ◽  
Basis Sets ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Structural And Electronic Properties ◽  
Rotationally Invariant

One of the main drawbacks in the density functional theory (DFT) formalism is the underestimation of the energy gaps in semiconducting materials. The combination of DFT with an explicit treatment of electronic correlation with a Hubbard-like model, known as DFT+<i>U</i> method, has been extensively applied to open up the energy gap in materials. Here, we introduce a systematic study where the selection of <i>U</i> parameter is analyzed considering two different basis sets: plane-waves (PWs) and numerical atomic orbitals (NAOs), together with different implementations for including <i>U</i>, to investigate the structural and electronic properties of a well-defined bipyramidal (TiO<sub>2</sub>)<sub>35 </sub>nanoparticle (NP). This study reveals, as expected, that a certain <i>U</i> value can reproduce the experimental value for the energy gap. However, there is a high dependence on the choice of basis set and, and on the +<i>U</i> parameter employed. The present study shows that the linear combination of the NAO basis functions, as implemented in FHI-aims, requires a lower <i>U</i> value than the simplified rotationally invariant approaches as implemented in VASP. Therefore, the transferability of <i>U</i> values between codes is unfeasible and not recommended, demanding initial benchmark studies for the property of interest as a reference to determine the appropriate value of <i>U</i>.

Geometrical and Electronic Structure Investigations of S-Doped Graphene

2013 ◽  
Vol 669 ◽  
pp. 144-148 ◽  
Author(s):  
Dong Mei Bi ◽  
Liang Qiao ◽  
Xiao Ying Hu ◽  
Shu Jie Liu
Keyword(s):  
Sulfur Atom ◽  
Electronic Structures ◽  
Density Functional ◽  
Generalized Gradient ◽  
Mulliken Population ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Level Shifts ◽  
Doped Graphene ◽  
Structure Investigations

The geometrical and electronic structures of pure graphene and S-doped graphene have been investigated using plane wave pseudopotential method with generalized gradient approximation based on the density functional theory. The local structure change, Mulliken population, density of states, and electron density difference of S-doped graphene have been calculated. It can be observed that the Fermi level shifts towards the conduction band after the doping of sulfur atom. The results also suggest that there are chemical bonds formed between the sulfur and carbon atoms, and the charges transfer from the doped sulfur atom to graphene.

scholarly journals On the Use of DFT+U to Describe the Electronic Structure of TiO2 Nanoparticles: (TiO2)35 as a Case Study

2020 ◽  
Author(s):  
Angel Morales ◽  
Stephen Rhatigan ◽  
Michael Nolan ◽  
Frances Illas
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Plane Waves ◽  
Basis Set ◽  
Basis Sets ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Structural And Electronic Properties ◽  
Rotationally Invariant

One of the main drawbacks in the density functional theory (DFT) formalism is the underestimation of the energy gaps in semiconducting materials. The combination of DFT with an explicit treatment of electronic correlation with a Hubbard-like model, known as DFT+<i>U</i> method, has been extensively applied to open up the energy gap in materials. Here, we introduce a systematic study where the selection of <i>U</i> parameter is analyzed considering two different basis sets: plane-waves (PWs) and numerical atomic orbitals (NAOs), together with different implementations for including <i>U</i>, to investigate the structural and electronic properties of a well-defined bipyramidal (TiO<sub>2</sub>)<sub>35 </sub>nanoparticle (NP). This study reveals, as expected, that a certain <i>U</i> value can reproduce the experimental value for the energy gap. However, there is a high dependence on the choice of basis set and, and on the +<i>U</i> parameter employed. The present study shows that the linear combination of the NAO basis functions, as implemented in FHI-aims, requires a lower <i>U</i> value than the simplified rotationally invariant approaches as implemented in VASP. Therefore, the transferability of <i>U</i> values between codes is unfeasible and not recommended, demanding initial benchmark studies for the property of interest as a reference to determine the appropriate value of <i>U</i>.

scholarly journals Synthesis and Characterization of Cu(I)-Folic Acid Complex A Theoretical and Experimental Study

2016 ◽  
Vol 13 (2) ◽  
pp. 121-127
Author(s):  
Baghdad Science Journal
Keyword(s):  
Folic Acid ◽  
Density Functional ◽  
Mulliken Charge ◽  
Mulliken Population ◽  
Acid Complex ◽  
Functional Theory ◽  
Acid Ligand ◽  
The Density Functional Theory ◽  
Homo Lumo

Copper (I) complex containing folic acid ligand was prepared and characterized on the basis of metal analyses, UV-VIS, FTIR spectroscopies and magnetic susceptibility. The density functional theory (DFT) as molecular modeling calculations was used to determine the donor atoms of folic acid ligand which appear clearly at oxygen atoms binding to hydrogen. Detection of donation sights is supported by theoretical parameters such as geometry, mulliken population, mulliken charge and HOMO-LUMO gap obtained by DFT calculations.

SERS Comparison from Au, Ag, and Au-Ag Alloys: Insights by the First Principles

2018 ◽  
Author(s):  
Masato Takenaka ◽  
Yoshikazu Hashimoto ◽  
Takeshi Iwasa ◽  
Tetsuya Taketsugu ◽  
Gediminas Seniutinas ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Functional Theory ◽  
Adsorption Models ◽  
Spectral Shifts ◽  
The Density Functional Theory ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

<div>Surface enhanced Raman scattering (SERS) is presented via a case study of 2,2’-bipyridyl</div><div>(22BPY) molecules adsorbed on pure Au and Ag as well as on Au-Ag alloy nanodiscs. Experimental</div><div>SERS spectra from Au and Ag nanodics show similar peaks, but those from Au-Ag alloy</div><div>reveal new spectral features. The physical enhancement factors due to surface nano-texture were</div><div>considered by numerical simulations of light intensity distribution for the nano-textured Au, Ag,</div><div>and Au-Ag alloy surfaces, but found to cause only minor differences. For the chemical insights of</div><div>enhancement, the density functional theory (DFT) calculations were performed using Au20, Ag20,</div><div>and Au10Ag10 clusters of a pyramidal structure for SERS modeling. Binding of 22BPY to the clusters</div><div>was simulated by considering possible arrangements of vertex and planar physical as well as</div><div>chemical adsorption models. A qualitative match with experimental SERS results for the pure Au</div><div>and Ag was obtained. DFT models showing spectral shifts of 22BPY SERS on the alloy nanodiscs</div><div>are presented.</div>

SERS Comparison from Au, Ag, and Au-Ag Alloys: Insights by the First Principles

2018 ◽  
Author(s):  
Masato Takenaka ◽  
Yoshikazu Hashimoto ◽  
Takeshi Iwasa ◽  
Tetsuya Taketsugu ◽  
Gediminas Seniutinas ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Functional Theory ◽  
Adsorption Models ◽  
Spectral Shifts ◽  
The Density Functional Theory ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

<div>Surface enhanced Raman scattering (SERS) is presented via a case study of 2,2’-bipyridyl</div><div>(22BPY) molecules adsorbed on pure Au and Ag as well as on Au-Ag alloy nanodiscs. Experimental</div><div>SERS spectra from Au and Ag nanodics show similar peaks, but those from Au-Ag alloy</div><div>reveal new spectral features. The physical enhancement factors due to surface nano-texture were</div><div>considered by numerical simulations of light intensity distribution for the nano-textured Au, Ag,</div><div>and Au-Ag alloy surfaces, but found to cause only minor differences. For the chemical insights of</div><div>enhancement, the density functional theory (DFT) calculations were performed using Au20, Ag20,</div><div>and Au10Ag10 clusters of a pyramidal structure for SERS modeling. Binding of 22BPY to the clusters</div><div>was simulated by considering possible arrangements of vertex and planar physical as well as</div><div>chemical adsorption models. A qualitative match with experimental SERS results for the pure Au</div><div>and Ag was obtained. DFT models showing spectral shifts of 22BPY SERS on the alloy nanodiscs</div><div>are presented.</div>

Fe-DOPED Ga12N12 CLUSTERS: ELECTRONIC AND MAGNETIC PROPERTIES

2013 ◽  
Vol 27 (30) ◽  
pp. 1350222 ◽  
Author(s):  
PENGFEI LU ◽  
CHENGJIE WU ◽  
ZIXIANG CONG ◽  
YILUAN LI ◽  
XIANLONG ZHANG ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Moment ◽  
Density Functional ◽  
Population Analysis ◽  
Mulliken Population Analysis ◽  
Mulliken Population ◽  
Functional Theory ◽  
Electronic And Magnetic Properties ◽  
The Density Functional Theory ◽  
Endohedral Doping

In this paper, we have investigated the structural, electronic and magnetic properties of Ga 12 N 12 cluster doped with monodoped and bidoped Fe atoms within the density functional theory (DFT). Substitutional, exohedral and endohedral doping are considered. It is observed that both monodoped and bidoped clusters tend to be in exohedral doping. Mulliken population analysis is performed to obtain the charge transfer and magnetic moment. The magnetic moment is mainly derived from 3d orbitals of Fe atom for all isomers, while the magnetic properties would rely on the Fe – Fe distance.

scholarly journals Comparative Atomic-Level Analysis of Sorption and Diffusion Properties of Membrane Materials on the Base of Polymer and Its Prepolymer: A Case Study of Polyheteroarylenes

Membranes ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 925
Author(s):  
Andrey V. Petrov ◽  
Alexander M. Toikka
Keyword(s):  
Density Functional ◽  
Atomic Level ◽  
Polymeric Membranes ◽  
Material Structure ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Dynamics Simulations ◽  
And Diffusion ◽  
Level Analysis

The sorption properties of polymers and the mobility of penetrants are the main factors which determine the trans-membrane processes. Other factors concern the membrane material structure and chemical nature. In this paper, we consider the case of polymers with similar structure units, namely a polymer and its pre-polymer (polybenzoxazinoneimide and imide-containing polyamic acid). The available experimental data show a great difference in the pervaporation process using these two polymeric membranes. Some explanation of this difference can be found at the atomic-level study. A comparative analysis of the diffusion of water and isopropanol molecules was carried out using the density functional theory and molecular dynamics simulations

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