Molecular structure, Mulliken charge, frontier molecular orbital and first hyperpolarizability analysis on 2-nitroaniline and 4-methoxy-2-nitroaniline using density functional theory

2014 ◽  
Vol 124 ◽  
pp. 199-202 ◽  
Author(s):  
S. Azhagiri ◽  
S. Jayakumar ◽  
S. Gunasekaran ◽  
S. Srinivasan
Keyword(s):  
Molecular Structure ◽  
Density Functional Theory ◽  
Molecular Orbital ◽  
Density Functional ◽  
Frontier Molecular Orbital ◽  
Mulliken Charge ◽  
First Hyperpolarizability ◽  
Functional Theory

scholarly journals Structural, Electronic, Molecular Orbital Analysis and Charge Distributions on Nitrate Salt of Guanidine through DFT and TD-DFT Methods

2021 ◽  
Vol 33 (8) ◽  
pp. 1905-1910
Author(s):  
S. Thangarasu ◽  
V. Siva ◽  
A. Shameem ◽  
A. Murugan ◽  
S. Athimoolam ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Ion Pairs ◽  
Frontier Molecular Orbital ◽  
Mulliken Charge ◽  
Functional Theory ◽  
Td Dft ◽  
Guanidinium Nitrate

Guanidinium nitrate, a non-linear optical material has been systematically studied through quantum chemical (density functional theory and Hartree Fock) methods. Studies on Mulliken charge, Frontier molecular orbitals (FMOs) and hyperpolarizability analyses have been performed. The Mulliken population analyses were carried out for the optimized molecular geometry by HF and B3LYP methods with 6-311++G(d,p) levels. The molecular orbital parameters of guanidinium nitrate have been calculated by FMO analysis. Frontier molecular orbital (FMO) analysis indicates the electron delocalization on the guanidinium nitrate and also its low value of energy gap indicates electron transfer. Optical property has been investigated by time-dependent density functional theory (TD-DFT) calculation. The second-order hyperpolarizability value of the ion pairs is much greater than urea, which confirms the good NLO nature of guanidinium nitrate.

EFFECT OF ASYMMETRIC LATERAL LINKING GROUPS ON THE ELECTRONIC TRANSPORT IN MOLECULAR DEVICE

2021 ◽  
Author(s):  
YAMIN WU ◽  
BIN LIAO ◽  
GUOLIANG WANG ◽  
BAOAN Bian
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Electronic Transport ◽  
Density Functional ◽  
Molecular Junctions ◽  
Frontier Molecular Orbital ◽  
Asymmetric Distribution ◽  
Molecular Device ◽  
Functional Theory ◽  
Lateral Linking

The effect of asymmetric lateral linking groups on the electronic transport is investigated in the biphenyl molecule-based device with gold electrodes with the framework of density functional theory and nonequilibrium Green’s function. The asymmetric lateral linking groups reduce the currents of molecular junctions, and result in the reverse rectifying behavior. The devices with asymmetric lateral linking groups –SH and –SCH3 have maximum rectifying ratios, while the asymmetric lateral linking group –SH and –NH2 cause minimum rectifying ratios. The calculated results suggest that the asymmetric lateral linking group induces the reduced coupling between molecule and right electrode, asymmetric distribution of frontier molecular orbital and asymmetric evolution of the molecular orbital eigenenergies, accounting for the rectifying behavior.

Structure and electronic properties of GaN tubelike clusters and single-walled GaN nanotubes

2015 ◽  
Vol 29 (17) ◽  
pp. 1550116 ◽  
Author(s):  
Liren Liu ◽  
Yanbo Zou ◽  
Hengjiang Zhu
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Electronic Properties ◽  
Molecular Orbital ◽  
Density Functional ◽  
Frontier Molecular Orbital ◽  
Structural Units ◽  
Functional Theory ◽  
Size Dependent ◽  
Molecular Orbital Surfaces

Extensive studies of the geometric structures, stabilities and electronic properties of gallium nitride (GaN)n tubelike clusters and single-walled GaN nanotubes (GaNNTs) were carried out using density-functional theory (DFT) calculations. A family of stable tubelike structures with Ga–N alternating arrangement was observed when n≥8 and their structural units (four-membered rings (4MRs) and six-membered rings (6MRs)) obey the general developing formula. The size-dependent properties of the frontier molecular orbital surfaces explain why the long and stable tubelike clusters can be obtained successfully. They also illustrate the reason why GaNNTs can be synthesized experimentally. Our results also reveal that the single-walled GaNNTs, which as semiconductors with a large bandgap, can be prepared by using the proper assembly of tubelike clusters.

Molecular structure, spectroscopic (IR, Raman, Ultra Violet-Visible) and nonlinear optical investigation on DCBLPZ: A novel semiorganic NLO material

2015 ◽  
Vol 14 (08) ◽  
pp. 1550061 ◽  
Author(s):  
Mohammed Shkir ◽  
V. K. Jain ◽  
S. AlFaify ◽  
M. M. Abutalib ◽  
I. S. Yahiya ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Molecular Orbital ◽  
Density Functional ◽  
Nonlinear Optical ◽  
Intramolecular Charge Transfer ◽  
Ultra Violet ◽  
First Hyperpolarizability ◽  
Functional Theory ◽  
Good Agreement

Dichlorobis(L-proline) zinc(II) (DCBLPZ) is an excellent nonlinear optical (NLO) material because of its ability to exhibit high second harmonic generation and having significant optical transparency. In this work, electro-optical properties of the titled material has been thoroughly investigated by Hartree–Fock (HF) and Density functional theory using different basis sets in C1 symmetry. The calculated geometrical parametres and vibrational frequencies were found to be in good agreement with reported experimental results. Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) studies were carried out to understand the intramolecular charge transfer within the molecule. Total dipole moment ([Formula: see text]), polarizability ([Formula: see text]), anisotropy of polarizability ([Formula: see text] and first hyperpolarizability ([Formula: see text]) values were calculated. The static first hyperpolarizability value is found to be six times higher than urea. Ultra violet-visible spectrum of DCBLPZ molecule was calculated by time-dependent density functional theory (TD-DFT) in gas phase using different functionals. The calculated value of absorption wavelength was found at 234[Formula: see text]nm using TD-B3LYP/[Formula: see text]* level of theory and was in good agreement with experimental value (230[Formula: see text]nm) than other applied methods. Our results give us flexibilty to predict about possible intramolecular charge transfer from both the chlorine atoms toward both the proline units through zinc atom in the studied metallic complex. The other important parametres such as frontier molecular orbital’s (FMO), global reactivity descriptors and molecular electrostatic potential have also been calculated and discussed.

On the Nature of Halide-Water Interactions: Insights from Many-Body Representations and Density Functional Theory

2019 ◽  
Author(s):  
Brandon B. Bizzarro ◽  
Colin K. Egan ◽  
Francesco Paesani
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Molecular Orbital ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Orbital Energy ◽  
Energy Decomposition Analysis ◽  
Interaction Energies ◽  
Many Body ◽  
Functional Theory

<div> <div> <div> <p>Interaction energies of halide-water dimers, X<sup>-</sup>(H<sub>2</sub>O), and trimers, X<sup>-</sup>(H<sub>2</sub>O)<sub>2</sub>, with X = F, Cl, Br, and I, are investigated using various many-body models and exchange-correlation functionals selected across the hierarchy of density functional theory (DFT) approximations. Analysis of the results obtained with the many-body models demonstrates the need to capture important short-range interactions in the regime of large inter-molecular orbital overlap, such as charge transfer and charge penetration. Failure to reproduce these effects can lead to large deviations relative to reference data calculated at the coupled cluster level of theory. Decompositions of interaction energies carried out with the absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA) method demonstrate that permanent and inductive electrostatic energies are accurately reproduced by all classes of XC functionals (from generalized gradient corrected (GGA) to hybrid and range-separated functionals), while significant variance is found for charge transfer energies predicted by different XC functionals. Since GGA and hybrid XC functionals predict the most and least attractive charge transfer energies, respectively, the large variance is likely due to the delocalization error. In this scenario, the hybrid XC functionals are then expected to provide the most accurate charge transfer energies. The sum of Pauli repulsion and dispersion energies are the most varied among the XC functionals, but it is found that a correspondence between the interaction energy and the ALMO EDA total frozen energy may be used to determine accurate estimates for these contributions. </p> </div> </div> </div>

A Density Functional Theory Study on the Ring-Opening Polymerization of D-Lactide Catalyzed by a Bifunctional-Thiourea Catalyst

2009 ◽  
Vol 62 (2) ◽  
pp. 157 ◽  
Author(s):  
Rong-Xiu Zhu ◽  
Ruo-Xi Wang ◽  
Dong-Ju Zhang ◽  
Cheng-Bu Liu
Keyword(s):  
Density Functional Theory ◽  
Ring Opening ◽  
Density Functional ◽  
Population Analysis ◽  
Density Functional Theory Calculations ◽  
Ring Opening Polymerization ◽  
Acyl Transfer ◽  
Frontier Molecular Orbital ◽  
Functional Theory ◽  
Elimination Pathway

The thiourea-catalyzed methanolysis of d-lactide, a model system for the initiation and propagation of the organocatalyzed ring-opening polymerization (ROP) of lactide, has been studied by performing density functional theory calculations. Both the catalyzed and uncatalyzed reactions are explored along two possible pathways: one involves the stepwise addition–elimination pathway and the other is related to the concerted pathway. It is found that the reaction without the presence of the catalyst is difficult because the barrier involved is as high as 176 kJ mol–1. With the aid of a thiourea catalyst, the barrier is reduced to 88 kJ mol–1 with a preference for the stepwise addition–elimination mechanism over the concerted one. The role of the catalyst has been rationalized by analyzing the frontier molecular orbital interactions between the catalyst and substrates and by performing natural population analysis. Finally, another mechanism involving acyl transfer is discussed for the thiourea-catalyzed ROP.

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