Influence of H, H2, O and O2 on Armchair SiGe Nanotubes: A Theoretical Study

2016 ◽  
Vol 16 (4) ◽  
pp. 3447-3456
Author(s):  
Prabath Wanaguru ◽  
Asok K Ray ◽  
Qiming Zhang
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Defect Density ◽  
Basis Set ◽  
Hybrid Functional ◽  
Lumo Energy ◽  
Adsorption Sites ◽  
The Difference ◽  
Controlled Adsorption

A systematic, hybrid density functional theory study of interaction between SiGe nanotubes (SiGeNTs) and X (X = H, O, H2 and O2) have been performed using the hybrid functional B3LYP and an all electron 3-21G* basis set implemented in GAUSSIAN 09 suite of software. All possible internal and external adsorption sites were considered, and it was found that H prefers to move onto top of an atom site while O prefers to incorporate into NT wall by breaking the bonds. Adsorption energies for H is ∼2.0 eV and for O it is ∼5.0 eV. Controlled adsorption of atomic H and several molecular O give rises to defect density states in the frontier orbital region. H rich adsorptions predict the difference between highest occupied molecular orbital (HOMO) energy and the lowest unoccupied molecular orbital (LUMO) energy increase while O rich adsorptions predict the decrease in HOMO-LUMO energy gap. O and O2 adsorptions predict definite ionic bonding character while H atomic adsorptions predict covalent bonding. H2 is very neutral towards the adsorption into SiGeNTs and clearly shows the physisorption adsorption. Considering the all adsorptions, the adsorptions happened within the Si vicinity of the SiGeNT shows the most stable and preferred adsorption region.

scholarly journals Theoretical and X-ray diffraction studies of organic photovoltaic compounds

2014 ◽  
Vol 70 (a1) ◽  
pp. C996-C996
Author(s):  
Abdelkader Chouaih ◽  
Salem Yahiaoui ◽  
Nadia Benhalima ◽  
Manel Boulakoud ◽  
Rachida Rahmani ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Organic Semiconductor ◽  
Density Functional ◽  
Energy Gap ◽  
Three Dimensional ◽  
Basis Set ◽  
X Ray Diffraction ◽  
Hybrid Functional ◽  
X Ray ◽  
Lowest Unoccupied Molecular Orbital

The electronic and structural properties of thiazolic ring derivatives were studied using density functional theory (DFT) and X-ray diffraction in terms of their application as organic semiconductor materials in photovoltaic devices. The B3LYP hybrid functional in combination with Pople type 6-31G(d) basis set with a polarization function was used in order to determine the optimized geometries and the electronic properties of the ground state, while transition energies and excited state properties were obtained from DFT with B3LYP/6-31G(d) calculation. The investigation of thiazolic derivatives formed by the arrangement of several monomeric units revealed that three-dimensional (3D) conjugated architectures present the best geometric and electronic characteristics for use as an organic semiconductor material. The highest occupied molecular orbital (HOMO) . lowest unoccupied molecular orbital (LUMO) energy gap was decreased in 3D structures that extend the absorption spectrum toward longer wavelengths, revealing a feasible intramolecular charge transfer process in these systems. All calculations in this work were performed using the Gaussian 03 W software package.

SOLVENT EFFECTS ON THE ELECTRONIC STRUCTURE AND NON-LINEAR OPTICAL PROPERTIES OF PYRENE AND SOME OF ITS DERIVATIVES BASED ON DENSITY FUNCTIONAL THEORY

2021 ◽  
Vol 4 (4) ◽  
pp. 236-251
Author(s):  
A. S. Gidado ◽  
L. S. Taura ◽  
A. Musa
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Energy Gap ◽  
Chemical Reactivity ◽  
Basis Set ◽  
Lumo Energy ◽  
Functional Theory ◽  
Organic Optoelectronic ◽  
Homo Lumo

Pyrene (C16H10) is an organic semiconductor which has wide applications in the field of organic electronics suitable for the development of organic light emitting diodes (OLED) and organic photovoltaic cells (OPV). In this work, Density Functional Theory (DFT) using Becke’s three and Lee Yang Parr (B3LYP) functional with basis set 6-311++G(d, p) implemented in Gaussian 03 package was  used to compute total energy, bond parameters, HOMO-LUMO energy gap, electron affinity, ionization potential, chemical reactivity descriptors, dipole moment, isotropic polarizability (α), anisotropy of polarizability ( Δ∝) total first order hyper-polarizability () and second order hyperpolarizability (). The molecules used are pyrene, 1-chloropyrene and 4-chloropyrene  in gas phase and in five different solvents: benzene, chloroform, acetone, DMSO and water. The results obtained show that solvents and chlorination actually influenced the properties of the molecules. The isolated pyrene in acetone has the largest value of HOMO-LUMO energy gap of and is a bit closer to a previously reported experimental value of  and hence is the most stable. Thus, the pyrene molecule has more kinetic stability and can be described as low reactive molecule. The calculated dipole moments are in the order of 4-chloropyrene (1.7645 D) < 1-chloropyrene (1.9663 D) in gas phase. The anisotropy of polarizability ( for pyrene and its derivatives were found to increase with increasing polarity of the solvents.  In a nutshell, the molecules will be promising for organic optoelectronic devices based on their computed properties as reported by this work.

scholarly journals Theoretical Study of a Class of Organic D-π-A Dyes for Polymer Solar Cells: Influence of Various π-Spacers

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 163
Author(s):  
Nguyen Van Trang ◽  
Tran Ngoc Dung ◽  
Ngo Tuan Cuong ◽  
Le Thi Hong Hai ◽  
Daniel Escudero ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Solar Cells ◽  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Polymer Solar Cells ◽  
Basis Set ◽  
Structure Theory ◽  
Functional Theory ◽  
Alkyl Groups

A class of D-π-A compounds that can be used as dyes for applications in polymer solar cells has theoretically been designed and studied, on the basis of the dyes recently shown by experiment to have the highest power conversion efficiency (PCE), namely the poly[4,8-bis(5-(2-butylhexylthio)thiophen-2-yl)benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl-alt-TZNT] (PBDTS-TZNT) and poly[4,8-bis(4-fluoro-5-(2-butylhexylthio)thiophen-2-yl)benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl-alt-TZNT] (PBDTSF-TZNT) substances. Electronic structure theory computations were carried out with density functional theory and time-dependent density functional theory methods in conjunction with the 6−311G (d, p) basis set. The PBDTS donor and the TZNT (naphtho[1,2-c:5,6-c]bis(2-octyl-[1,2,3]triazole)) acceptor components were established from the original substances upon replacement of long alkyl groups within the thiophene and azole rings with methyl groups. In particular, the effects of several π-spacers were investigated. The calculated results confirmed that dithieno[3,2-b:2′,3′-d] silole (DTS) acts as an excellent π-linker, even better than the thiophene bridge in the original substances in terms of well-known criteria. Indeed, a PBDTS-DTS-TZNT combination forms a D-π-A substance that has a flatter structure, more rigidity in going from the neutral to the cationic form, and a better conjugation than the original compounds. The highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gap of such a D-π-A substance becomes smaller and its absorption spectrum is more intense and red-shifted, which enhances the intramolecular charge transfer and makes it a promising candidate to attain higher PCEs.

Theoretical study of 11-thiocyanatoundecanoic acid phenylamide derivatives on corrosion inhibition efficiencies

2014 ◽  
Vol 92 (9) ◽  
pp. 876-887 ◽  
Author(s):  
Seda Sagdinc ◽  
Yesim Kara ◽  
Filiz Kayadibi
Keyword(s):  
Density Functional ◽  
Corrosion Inhibitors ◽  
Energy Gap ◽  
Basis Set ◽  
Inhibitor Molecule ◽  
Functional Theory ◽  
Fukui Functions ◽  
Reactivity Descriptors ◽  
Hartree Fock ◽  
Adsorption Sites

Ab initio Hartree–Fock (HF) and Density Functional Theory (DFT) B3LYP methods with the 6-311G(d,p) basis set were applied to the three 11-thiocyanatoundecanoic acid phenylamide derivatives as corrosion inhibitors. Inhibition efficiency obtained experimentally followed the following order: N-(4-methoxyphenyl)-11-thiocyanatoundecanamide (N3MPTUA) > N-phenyl-11-thiocyanatoundecanamide (NPTUA) > N-(3-nitrophenyl)-11-thiocyanatoundecanamide (N3NPTUA). The molecular parameters most relevant to their potential action as corrosion inhibitors have been calculated in the neutral and protonated forms: EHOMO, ELUMO, energy gap (ΔE), dipole moment (μD), electronegativity (χ), global hardness (η), and the fraction of electrons transferred from the inhibitor molecule to the metallic atom (ΔN). The results of most of the global reactivity descriptors show that the experimental and theoretical studies agree well, and confirm that N3MPTUA is a better inhibitor than NPTUA or N3NPTUA. In addition, the local reactivity, analyzed through Fukui functions, show that the oxygen and nitrogen atoms will be the main adsorption sites.

scholarly journals Molecular properties of polyvinyl alcohol/ sodium alginate composite

2019 ◽  
Vol 10 (1) ◽  
pp. 4734-4739
Keyword(s):  
Polyvinyl Alcohol ◽  
Sodium Alginate ◽  
Density Functional ◽  
Energy Gap ◽  
Heat Of Formation ◽  
Thermal Parameters ◽  
Basis Set ◽  
Lumo Energy ◽  
Model Structures ◽  
Homo Lumo

Molecular and bimolecular properties are important factors to judge the functionality of polymer/biopolymer composites. Accordingly, molecular modeling is conducted to study the electronic properties of Polyvinyl Alcohol (PVA); Sodium Alginate (SA) as well as their composites. Accordingly, Density functional theory (DFT) at B3LYB level using 6-311/G (d, p) basis set is utilized to study the model structures. Total dipole moment (TDM), HOMO/LUMO energy gap, electrostatic potential (ESP) are calculated at B3LYB level for all studied structures. The results of TDM, HOMO/LUMO energy gap and ESP indicated that the TDM increased, HOMO/LUMO energy gap decreased and electro-negativity increased for the structures under study. Thermal parameters at PM6 are calculated including final heat of formation; free energy; entropy; enthalpy and heat capacity as a function of temperature. Thermal parameters show a variation with changing the site of interaction which indicated that the coordination of PVA/SA is an important factor for describing PVA/SA composite.

scholarly journals Computational studies of the thermodynamic properties, and global and reactivity descriptors of fluorescein dye derivatives in acetonitrile using density functional theory

2021 ◽  
pp. 174751982199451
Author(s):  
Juma Mzume Juma ◽  
Said AH Vuai
Keyword(s):  
Density Functional Theory ◽  
Thermodynamic Properties ◽  
Ionization Potential ◽  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Basis Sets ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Reactivity Descriptors

This work reports density functional theory calculations of the optimized geometries, molecular reactivity, energy gap, and thermodynamic properties of molecular dyes fluorescein (FS), fluorescein attached with methoxy (FSO), fluorescein attached with amine (FSA), fluorescein attached with methane (FSM), fluorescein attached with ethene (FSE), and fluorescein attached with thiophene (FST) using the hybrid functional B3LYP and 6-311G basis sets. When donating groups are attached to the molecular dye, the bond lengths are slightly decreased which is important for easy transfer of electron from donating to the accepting group. For all dyes, highest occupied molecular orbital/lowest occupied molecular orbital analysis results in positive outcomes upon electron injection to semiconductors and subsequent dye regeneration by the electrolyte. The ionization potential increases with increasing conjugation; therefore, the molecular dye attached to thiophene has the highest ionization potential. Meanwhile, a donating group with increased conjugation results in low electron affinity.

Theoretical studies on lindqvist polyoxometalates [M6O19]n−(M = Mo, W, n=2; M = V, Nb, Ta, n=8) and derivatives: Electronic structures, stability and bonding

2017 ◽  
Vol 16 (06) ◽  
pp. 1750054 ◽  
Author(s):  
Xiao-Fang Su ◽  
Bo Zhu ◽  
Cai-Xia Wu ◽  
Li-Kai Yan ◽  
Zhong-Min Su
Keyword(s):  
Charge Density ◽  
Molecular Orbital ◽  
Electronic Structures ◽  
Density Functional ◽  
Geometrical Structure ◽  
Energy Gap ◽  
Lumo Energy ◽  
Functional Theory ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

The geometrical and electronic structures of [M6O[Formula: see text]][Formula: see text] (M [Formula: see text] Mo, W, [Formula: see text]; M [Formula: see text] V, Nb, Ta, [Formula: see text]) and their derivatives were investigated by using density functional theory methods. The results indicate that the geometrical structure of [V6O[Formula: see text]][Formula: see text] is not different from other Lindqvist-type anions. The energy gap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) (HOMO[Formula: see text]LUMO energy gap) of [V6O[Formula: see text]][Formula: see text] is smaller than those of same charge anions, [Nb6O[Formula: see text]][Formula: see text] and [Ta6O[Formula: see text]][Formula: see text]. In addition, the charge density [Formula: see text] of [V6O[Formula: see text]][Formula: see text] is larger when compared with those of other studied clusters. The investigation on the derivatives shows that the valence of V atom (V[Formula: see text] or V[Formula: see text]) and the methoxy ligand influence the HOMO[Formula: see text]LUMO energy gap and the charge density [Formula: see text] of the studied clusters.

Revealing the Inhibition Efficiencies of Artesunate and Rutin for Corrosion of Steel: A Theoretical Study

2018 ◽  
Vol 762 ◽  
pp. 325-329 ◽  
Author(s):  
Gökhan Gece
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Theoretical Calculations ◽  
Aqueous Media ◽  
Basis Set ◽  
Orbital Energy ◽  
Molecular Orbital Energy ◽  
Experimental Findings ◽  
Corrosion Of Steel

Corrosion inhibition characteristics of artesunate and rutin on carbon steel in water has been studied using density functional theory (DFT). Quantum chemical parameters such as highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), energy gap (ΔE), and global reactivity properties have been calculated at the B3LYP/6-311G(d,p) basis set. The results of theoretical calculations confirm the experimental findings on the superiority of rutin to protect the corrosion of steel in aqueous media compared to artesunate.

Electronic Structures and Spectroscopic Properties of Fluorescent Sensor Reacting with Volatile Organic Compounds: A Theoretical Analysis

2021 ◽  
Vol 16 (4) ◽  
pp. 584-590
Author(s):  
Haiyang Gu ◽  
Xingyi Huang ◽  
Quansheng Chen ◽  
Chin Ping Tan ◽  
Yanhui Sun
Keyword(s):  
Density Functional Theory ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Basis Set ◽  
Functional Theory ◽  
Array Sensor ◽  
Volatile Organic

A theoretical study of copper porphyrin (CuP), without any meso substituent, reacting with different volatile organic compounds (VOCs), recently applied as the dye in the fluorescent array sensor was calculated for the ground and excited electronic states. Geometry structures of CuP and its complexes were optimized by using density functional theory coupled with B3LYP/LAN2DZ basis set, whereas excitation energies were calculated by time-dependent density functional theory at the same level. The calculated relative energies of CuP and its complexes have displayed the following order: CuP-L6 < CuP-L1 < CuP-H2S < CuP < CuP-L4 < CuP-L2 < CuP-O2 < CuP-L5 < CuP-L3. The relative energies between CuP and propionaldehyde (L6) possess the lowest energy gap, causing the binding to react more efficiently and faster than the other complexes. The results also reveal that the addition of VOCs has a significant influence on the spectrum property and energy gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). This study suggests that the calculation result is useful for the application of a CuP-based fluorescent array sensor for a special analyte.

scholarly journals Synthesis, characterization, DFT, and TD-DFT studies of (E)-5-((4,6-dichloro-1,3,5-triazin-2-yl)amino)-4-hydroxy-3-(phenyldiazenyl)naphthalene-2,7-diylbis(hydrogen sulfite)

2021 ◽  
Vol 3 (7) ◽  
Author(s):  
Hitler Louis ◽  
Obieze C. Enudi ◽  
Joseph O. Odey ◽  
Izubundu B. Onyebuenyi ◽  
Azuaga T. Igbalagh ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Nbo Analysis ◽  
Basis Set ◽  
Orbital Interactions ◽  
B3lyp Method ◽  
Td Dft ◽  
Donor Acceptor ◽  
Molecular Orbital Analysis

AbstractIn this study, (E)-5-((4,6-dichloro-1,3,5-triazin-2-yl)amino)-4-hydroxy-3-(phenyldiazenyl)naphthalene-2,7-diylbis(hydrogen sulfite), a cyanurated H-acid (CHA) azo dye, was synthesized and characterized using FT-IR spectrophotometer and GC-MS spectroscopy. A density functional theory (DFT) based B3LYP and CAM-B3LYP method with 6–311 + G (d,p) basis set analysis was computed for HOMO-LUMO, natural bonding orbitals (NBO), UV-Vis absorptions and excitation interactions, in order to understand its molecular orbital excitation properties. A low Energy gap (Eg) of 2.947 eV was obtained from the molecular orbital analysis, which showed that HOMO to LUMO transition is highly feasible; hence CHA is adequate for diverse electronic and optic applications. Studies of the first five excitations (S0 → S1/S2/S3/S4/S5) of CHA revealed that S0 → S1 and S0 → S3 are π → π* type local excitations distributed around the –N=N– group; S0 → S2, a Rydberg type local excitation; S0 → S4, a highly localized π → π* excitation; while S0 → S5 is an n → π* charge transfer from a benzene ring to –N=N– group. From NBO analysis, we obtained the various donor–acceptor orbital interactions contributing to the stabilization of the studied compound. Most significantly, some strong hyper-conjugations (n → n*) within fragments, and non-bondingand anti-bonding intermolecular (n → n*/π* and π → n*/π*) interactions were observed to contribute appreciable energies. This study is valuable for understanding the molecular properties of the azo dyes compounds and for synthesizing new ones in the future.

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