scholarly journals Determination of Optical Parameters of Films of PVA/TiO2/SiC and PVA/MgO/SiC Nanocomposites for Optoelectronics and UV-Detectors

2020 ◽  
Vol 65 (6) ◽  
pp. 533 ◽  
Author(s):  
H. Ahmed ◽  
A. Hashim ◽  
H. M. Abduljalil
Keyword(s):  
Density Functional ◽  
Low Cost ◽  
Dielectric Constants ◽  
Basis Set ◽  
Optical Parameters ◽  
Functional Theory ◽  
Uv Detectors ◽  
Light Filters ◽  
The Density Functional Theory

The optical properties of polyvinyl alcohol (PVA)–titanium oxide (TiO2)–silicon carbide (SiC) and (PVA)–magnesium oxide (MgO)–(SiC) nanocomposites are calculated, by using the Gaussian 09 and Gaussian view 5.0.8 programs on the basis of the density functional theory at B3LYP level with 6–31 G basis set. The results indicate that the absorbance, absorption coefficient, extinction coefficient, refractive index, imaginary and real dielectric constants, and optical conductivity of (PVA–TiO2–SiC) and (PVA–MgO–SiC) increase with the concentration of SiC nanoparticles. Both nanocomposites have high absorbance in the UV region and have indirect energy gaps 1 eV < Eg < 2.2 eV. This makes them useful for various applications in optoelectronics, photovoltaics, lasers, solar cells, sensors, photocatalytic devices, light filters, UV detectors, etc. with low cost, easy fabrication, and adaptability as compared with other devices.

Theoretical Study on Au-Doped Ge Semiconductor Clusters

2013 ◽  
Vol 634-638 ◽  
pp. 2537-2540
Author(s):  
Xiao Jun Li
Keyword(s):  
Vibrational Frequency ◽  
Density Functional ◽  
Theoretical Study ◽  
Chemical Shifts ◽  
Theoretical Work ◽  
Basis Set ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Germanium Clusters

Structure, electronic property, aromaticity and vibrational frequency of medium-sized Au-doped germanium clusters were systematically explored using the density-functional theory (DFT) in conjunction with the LanL2DZ basis set. Our results show that the endohedrally Au-doped cagelike structures are energetically preferred. The p- and d-states in endohedral Au atom mainly contribute to the chemical bonding at around −6.5 and −10.6 eV for the AuGe10 and AuGe12 clusters. Moreover, the cage aromaticity appears to be an important determination of the electronic stability of the two clusters, reflected by negative nucleus-independent chemical shifts (NICS) values. The theoretical work will be useful and helpful for the understanding in the further application, i.e., cluster-assembled optoelectronic nanomaterials.

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

2021 ◽  
Vol 43 (1) ◽  
pp. 25-25
Author(s):  
Said Abdelqadar Said Said Abdelqadar Said ◽  
Omar A Shareef and Abdulkhalik S Alkazzaz Omar A Shareef and Abdulkhalik S Alkazzaz
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Ring Closure ◽  
Basis Set ◽  
Functional Theory ◽  
Rate Determining Step ◽  
The Density Functional Theory ◽  
Electronic And Structural Properties ◽  
Maximum Hardness Principle

The transformation of 2and#39;-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

scholarly journals First-Principles Determination of the Polarizabilities of Carbon Tubules as a Function of Length

1994 ◽  
Vol 349 ◽  
Author(s):  
Andrew A. Quong ◽  
Mark R. Pederson
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Valence Electron ◽  
Local Density ◽  
Density Approximation ◽  
Functional Theory ◽  
Size Dependent ◽  
The Density Functional Theory ◽  
Linear And Nonlinear

ABSTRACTWe use the local-density-approximation to the density-functional theory to determine the axial polarizabilities of fullerene tubules as a function of length and winding topologies. Specifically, we present linear polarizabilities for tubules of composition C12H24, C36H24, C40H20 and C60H24. The size-dependent variation in the dipole-coupled gaps between pairs of occupied and unoccupied levels leads to enhancements in the polarizability per valence electron as the length of the tubule increases. The results are compared to recent densityfunctional based calculations of the linear and nonlinear polarizabilities for fullerene and benzene molecules.

scholarly journals Analysis of vibratinal spectra of 8-hydroxyquinoline and its 5,7-dichloro, 5,7-dibromo, 5,7-diiodo and 5,7-dinitro derivatives based on density functional theory calculations

2007 ◽  
Vol 5 (1) ◽  
pp. 201-220 ◽  
Author(s):  
Khaled Bahgat ◽  
Abdel Ragheb
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Basis Set ◽  
Normal Coordinate ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Vibrational Bands ◽  
Good Agreement

AbstractThe geometry, frequency and intensity of the vibrational bands of 8-hydroxyquinoline and its 5,7-dichloro, 5,7-dibromo, 5,7-diiodo and 5,7-dinitro derivatives were obtained by the density functional theory (DFT) calculations with Becke3-Lee-Parr (B3LYP) functional and 6-31G* basis set. The effects of chloride, bromide, iodide and nitro substituent on the vibrational frequencies of 8-hydroxyquinoline have been investigated. The assignments have been proposed with aid of the results of normal coordinate analysis. The observed and calculated spectra are found to be in good agreement.

scholarly journals The difference in stability between 5′R and 5′S diastereomers of 5′,8-cyclopurine-2′-deoxynucleosides. DFT study in gaseous and aqueous phase

2010 ◽  
Vol 8 (1) ◽  
pp. 134-141 ◽  
Author(s):  
Boleslaw Karwowski
Keyword(s):  
Density Functional ◽  
Bond Cleavage ◽  
Basis Set ◽  
Small Range ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Formic Acid Hydrolysis ◽  
The Difference ◽  
The Stability ◽  
First Time

AbstractOxidatively generated damage to DNA frequently appears in the human genome as an effect of aerobic metabolism or as the result of exposure to exogenous oxidizing agents. Due to these facts it has been decided to calculate the stability of 5′,8-cyclo-2′-deoxyadenosine/guanosine (cdA, cdG) in their 5′R and 5′S diastereomeric forms. For all points of quantum mechanics studies presented, the density functional theory (DFT) with B3LYP parameters on 6-311++G** basis set level was used. The calculations showed a significant negative enthalpy for glycosidic bond cleavage reaction for cationic forms and slightly negative for neutral ones. The preliminary study of the discussed process has shown the nature of stepwise nucleophilic substitution DN*AD type mechanism. Surprisingly, the different values in free energy, between short-lived oxacarbenium ion intermediates, have been found to lie over a relatively small range, around 1 and 2.8 kcal mol−1. For anions, the decomposition enthalpies were found as positive in aqueous phases. These theoretical results are supported by the formic acid hydrolysis experiments of both diastereomers of cdA, for the first time. (5′S)cdA exhibited higher stability than (5′R)cdA.

scholarly journals Structural characterization of kaempferol: a spectroscopic and computational study

2019 ◽  
Vol 38 (1) ◽  
pp. 49 ◽  
Author(s):  
Dejan Milenković ◽  
Jasmina M Dimitrić Marković ◽  
Dušan Dimić ◽  
Svetlana Jeremić ◽  
Dragan Amić ◽  
...  
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Chemical Shifts ◽  
Absolute Error ◽  
Nbo Analysis ◽  
Basis Set ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Spectroscopic Characteristics

Calculations based on the density functional theory, with the B3LYP functional and the 6-311++G(d,p) basis set, were performed with the aim of confirming the molecular structure and spectroscopic characteristics of kaempferol, a naturally occurring flavonoid molecule. The electronic structure of kaempferol was examined using NBO analysis. The assigning of the experimentally obtained IR and Raman spectra was performed after the best-fit-based comparison with theoretical spectra. The 13C and 1H NMR experimental spectra were related to the theoretically obtained values of the chemical shifts determined by the GIAO method. The correlation coefficient and the average absolute error values proved B3LYP-D3 to be an adequate method in describing the NMR parameters of kaempferol. Molecular docking analysis was carried out in order to identify the potency of inhibition of the title molecule against human procalcitonin. The inhibition activity was obtained for 10 conformations of ligand inside the protein.

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

2021 ◽  
Vol 43 (1) ◽  
pp. 25-25
Author(s):  
Said Abdelqadar Said Said Abdelqadar Said ◽  
Omar A Shareef and Abdulkhalik S Alkazzaz Omar A Shareef and Abdulkhalik S Alkazzaz
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Ring Closure ◽  
Basis Set ◽  
Functional Theory ◽  
Rate Determining Step ◽  
The Density Functional Theory ◽  
Electronic And Structural Properties ◽  
Maximum Hardness Principle

The transformation of 2and#39;-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

scholarly journals Noble gas cluster ions

2018 ◽  
Vol 174 ◽  
pp. 06003
Author(s):  
Yunus Kaya ◽  
Yalçin Kalkan ◽  
Rob Veenhof
Keyword(s):  
Density Functional ◽  
Noble Gas ◽  
Kinetic Studies ◽  
Basis Set ◽  
Cluster Ions ◽  
Functional Theory ◽  
B3lyp Method ◽  
Xenon Cluster ◽  
The Density Functional Theory ◽  
Potential Basis

In this work, a reaction mechanism of formation of noble gas (Ng) cluster ions has been theoretically investigated in detail. The kinetic studies of formation of Xe+Xe cluster in Xe, Ar+Ar cluster ions in Ar, and Ne+Ne cluster ions in Ne have been made as theoretically. The optimized structures in the ground state were calculated using the density functional theory (DFT) by the B3LYP method combined with the Stuttgart/Dresden effective core potential basis set (SDD). In addition, we calculated the rate constants of all cluster formations. The results are 1.15 × 10−31, 3.58 × 10−31, 0.23 × 10−31cm6/s, respectively for Neon, Argon, Xenon cluster ions.

scholarly journals Influence of water on the surface of graphene

2018 ◽  
Vol 174 ◽  
pp. 06002
Author(s):  
Yunus Kaya ◽  
Yalçin Kalkan ◽  
Rob Veenhof
Keyword(s):  
Density Functional Theory ◽  
Water Molecule ◽  
Density Functional ◽  
Theoretical Models ◽  
Surface Conductivity ◽  
Basis Set ◽  
Hybrid Functional ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Influence Of Water

We have studied how water modifies the surface of graphene and in particular how the surface conductivity of graphene is affected. According to the literature, two types of interactions should be distinguished: physical, where a water molecule remains intact and is located at some distance from the mesh, and chemical, where a water molecule is imbricated in the graphene bond structure. We have developed theoretical models for both types of interactions using the density functional theory (DFT) with the B3LYP hybrid functional combined with the 6-31G(d) basis set. Our calculations show that the surface conductivity of graphene is reduced in the presence of water.

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