scholarly journals Theoretical Study the Structure, Electronic and Spectra Properties for Nanotube Molecules by using DFT Method

2019 ◽  
Vol 14 (8) ◽  
pp. 10325-10330
Author(s):  
Rajaa K. Mohammad
Keyword(s):  
Theoretical Study ◽  
Dft Method ◽  
Spectra Properties

scholarly journals Theoretical Study of the Reaction of Formation of Some Free Phosphines by Stereoselective Hydrophosphination through DFT Method

2018 ◽  
pp. 1-10
Author(s):  
Kouadio Valery Bohoussou ◽  
Anoubilé Bénié ◽  
Mamadou Guy-Richard Koné ◽  
N’guessan Yao Silvère Diki ◽  
Kafoumba Bamba ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Chemical Reactivity ◽  
Dft Method ◽  
Trans Form ◽  
Dft Methods ◽  
Activation Barriers ◽  
Reactivity Descriptors ◽  
Chemical Reactivity Descriptors ◽  
Theoretical Results ◽  
Cis Isomer

In this work the formation of vinylphosphines was studied through the hydrophosphination reaction. The study aims to rationalize the stereoselectivity of these compounds using quantum DFT methods. This theoretical study of chemical reactivity was conducted at B3LYP/6-311 + G (d, p) level. Global chemical reactivity descriptors, stationary point energies and activation barriers were examined to foretell the relative stability of the stereoisomers formed. The various results obtained have revealed that the addition of arylphosphine to dihalogenoacetylene is stereospecific. The Trans form of vinylphosphines is more stable than the Cis form, when the substituent on phosphorus generates less or no π-conjugations. On the other hand, the Cis isomer is predominant when the aryl radical favors more π-conjugations. The theoretical results obtained are in agreement with the experimental results.

Experimental and theoretical study using DFT method for the competitive adsorption of two cationic dyes from wastewaters

2016 ◽  
Vol 390 ◽  
pp. 311-319 ◽  
Author(s):  
Abdelmajid Regti ◽  
Hicham Ben El Ayouchia ◽  
My Rachid Laamari ◽  
Salah Eddine Stiriba ◽  
Hafid Anane ◽  
...  
Keyword(s):  
Competitive Adsorption ◽  
Theoretical Study ◽  
Dft Method ◽  
Cationic Dyes

scholarly journals Structure cristalline, caractérisation spectroscopique, calcul DFT et analyse de surface Hirshfeld du perchlorate de p-toluidinium

2018 ◽  
Vol 74 (2) ◽  
pp. 91-97 ◽  
Author(s):  
Meriam Ben Jomaa ◽  
Hammouda Chebbi ◽  
Noura Fakhar Bourguiba ◽  
Mohamed Faouzi Zid
Keyword(s):  
Theoretical Study ◽  
Dft Method ◽  
Hirshfeld Surface ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Two Component ◽  
Graph Set ◽  
Molecular Layers ◽  
Good Agreement

The synthesis of p-toluidinium perchlorate (systematic name: 4-methylanilinium perchlorate), C7H10N+·ClO4 −, was carried out from an aqueous reaction of perchloric acid with p-toluidine. This compound was characterized by powder XRD, IR and UV–Vis spectroscopy. The structure was further confirmed by a single-crystal X-ray diffraction study. The crystal structure is formed by a succession of two-dimensional molecular layers consisting of perchlorate anions and organic cations parallel to the (100) plane and located at x = 2n + ½ (n ∈ Z). Each mixed layer is formed by infinite chains {C7H10N+·ClO4 −} n parallel to the [010] direction and developing along the c axis, generating R 2 4(8), R 2 2(4) and R 4 4(12) graph-set motifs. The results of a theoretical study using the DFT method at the B3LYP/6–311++G(d,p) level are in good agreement with the experimental data. Hirshfeld surface and fingerprint plots reveal that the structure is dominated by O...H/H...O (54.2%), H...H (26.9%) and C—H ...π (14.3%) contacts. The studied crystal was refined as a two-component twin

scholarly journals Theoretical study of metal composite based on pyrolyzed polyacrylonitrile monolayer containing Fe-Co, Ni-Co and Fe-Ni metal atom pairs and silicon amorphizing admixture

2020 ◽  
Vol 6 (3) ◽  
pp. 95-99
Author(s):  
Irina V. Zaporotskova ◽  
Daniel P. Radchenko ◽  
Lev V. Kozhitov ◽  
Pavel A. Zaporotskov ◽  
Alena V. Popkova
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Matrix Material ◽  
Wide Band ◽  
Dft Method ◽  
Metal Composite ◽  
Composite Systems ◽  
Metal Atoms ◽  
Transition Metal Atoms ◽  
Designed Materials

An urgent problem of radio engineering and radioelectronics nowadays is the synthesis of composite materials with preset parameters that can be used as electronics engineering materials. Of special interest are MW range wide-band electromagnetic radiation absorbers. Special attention is paid to materials on the basis of ferromagnetic metals that are capable of effectively absorbing and reflecting incident waves and having a clear nanostructure. Development of nanocapsulated metals will allow controlling the parameters of newly designed materials. This is achieved with the use of polymer matrices, e.g. pyrolyzed polyacrylonitrile (PPAN). This work is a theoretical study of a PPAN monolayer model containing pairs of transition metal atoms iron, nickel and cobalt which possess ferromagnetic properties, in Fe-Co, Ni-Co and Fe-Ni combinations, with silicon amorphizing admixture. We studied the geometrical structure of the metal composite systems which are modeled as PPAN molecular clusters the centers of which are voided of six matrix material atoms, the resultant defects (the so-called pores) being filled with pairs of the metal atoms being studied. The metal containing monolayer proved to be distorted in comparison with the initially planar PPAN monolayer. We plotted single-electron spectra of the composite nanosystems and characterized their band gaps. The presence of metal atoms reduces the band gap of a metal composite as compared with pure PPAN. We determined the charges of the metals and found electron density transfer from metal atoms to their adjacent PPAN monolayer atoms. We calculated the average bond energy of the test metal composite systems and proved them to be stable. The studies involved the use of the density functional theory (DFT) method with the B3LYP functional and the 6-31G(d) basis.

A Theoretical Study of Nonlinear Optical Properties for Stilbene Grafted to Carbon Nanotubes

2015 ◽  
Vol 1118 ◽  
pp. 149-153 ◽  
Author(s):  
Si Li ◽  
Yun Xia Wang ◽  
Zhao Di Yang
Keyword(s):  
Carbon Nanotubes ◽  
Optical Properties ◽  
Nonlinear Optical ◽  
Theoretical Study ◽  
Energy Gap ◽  
Dft Method ◽  
Amide Bond ◽  
Organic Chromophore ◽  
Equilibrium Geometries ◽  
Maximum Absorption Wavelength

DFT method was used to calculate the equilibrium geometries, electron structures and first-hyperpolarizabilities of grafted SWCNT (4,4) by organic chromophore stilbene at B3LYP/6-31G* level. ZINDO method was also used to calculate first-and second-hyperpolarizabilities. The calculated results show that stilbene graftings make the energy gap a little reduced and the maximum absorption wavelength red shifted, however grafting of stilbene breaks the symmetry of pure nanotube and lets hyperpolarizability increase obviously. We also found that grafting on tube mouth results in better nonlinear for their better conjugation and amide bond-linking shows bigger hyperpolarizabilities relative to direct bond-linking.

Theoretical study on the mechanism and enantioselectivity of NHC-catalyzed intramolecular SN2′ nucleophilic substitution: what are the roles of NHC and DBU?

2018 ◽  
Vol 5 (9) ◽  
pp. 1493-1501 ◽  
Author(s):  
Huimin Zhang ◽  
Hao Xu ◽  
Huining Bai ◽  
Donghui Wei ◽  
Yanyan Zhu ◽  
...  
Keyword(s):  
Nucleophilic Substitution ◽  
Catalytic Mechanism ◽  
Theoretical Study ◽  
Dft Method

A possible catalytic mechanism was proposed and studied in very detail by using the DFT method for a recently reported enantioselective intramolecular SN2′ substitution of aldehydes with trisubstituted allylic bromides.

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