scholarly journals NBO Population Analysis and Electronic Calculation of Four Azopyridine Ruthenium Complexes by DFT Method

2017 ◽  
Vol 05 (01) ◽  
pp. 51-64 ◽  
Author(s):  
N’Guessan Kouakou Nobel ◽  
Kafoumba Bamba ◽  
Ouattara Wawohinlin Patrice ◽  
Nahossé Ziao
Keyword(s):  
Population Analysis ◽  
Ruthenium Complexes ◽  
Dft Method ◽  
Electronic Calculation

Theoretical study of the geometrical and electronic properties of Be2Mg+ n (n = 1–11) clusters

2019 ◽  
Vol 9 (7) ◽  
pp. 778-785 ◽  
Author(s):  
Ben-Chao Zhu ◽  
Zhang Yu ◽  
Wang Ping ◽  
Lu Zeng ◽  
Shuai Zhang
Keyword(s):  
Electronic Properties ◽  
Ground State ◽  
Density Functional ◽  
Population Analysis ◽  
Dft Method ◽  
Mulliken Population ◽  
Functional Theory ◽  
Fragmentation Energy ◽  
Average Binding Energy ◽  
Ground State Structures

By using Density Functional Theory (DFT) method at the B3LYP/6-311G level, the structures, stabilities, and electronic properties of cationic Be2Mg+ n (n = 1–11) clusters have been systematically studied. The optimized geometry show that the ground state structures of cationic Be2Mg+ n (n = 1–11) clusters favor 3D structures except n = 1, 2. Furthermore, the average binding energy E b, the second-order energy differences Δ2E, the fragmentation energy Ef and the HOMO-LUMO energy Egap of the ground state of cationic Be2Mg– n (n = 1–11) clusters are calculated, the final results indicate that Be2Mg+6 and Be2Mg+9 clusters have a higher stability than other clusters. Additionally, the NCP, NEC and Mulliken population analysis reveal that the charges in cationic Be2Mg+ n (n = 1–11) clusters transfer from Mg atom to Be atoms, and strong sp hybridizations are presented in Be atoms of Be2Mg+ n clusters. Finally, the polarizability analysis indicates that the nuclei and electronic clouds of clusters are affected by external field with the increase of cluster size.

scholarly journals A computational NPA and NMR study of Li-capped armchair GaN nanotubes

2010 ◽  
Vol 8 (4) ◽  
pp. 913-918 ◽  
Author(s):  
Ahmad Seif ◽  
Temer Ahmadi
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Geometrical Structure ◽  
Population Analysis ◽  
Dft Method ◽  
Basis Sets ◽  
Chemical Shielding ◽  
Natural Population Analysis ◽  
Nmr Parameters ◽  
Nmr Study ◽  
First Time

AbstractThe geometrical structure, the nuclear magnetic resonance (NMR) parameters and natural population analysis (NPA) of the H-capped (raw) and Li-capped armchair single-walled gallium nitride nanotubes (GaNNTs) are computed and reported for the first time. Our results show that the variation of isotropic chemical shielding (ICS) parameters at the sites of 15N and 71Ga along the length of both models-raw and Li-capped- are reversed. The calculations were carried out with B3LYP-DFT method and 6–31G (d) standard basis sets using the Gaussian 03 suite of programs.

X-ray and DFT Investigation of (E)-4-bromo-5-methoxy-2-((o-tolylimino)methyl)phenol Compound

2018 ◽  
pp. 454-461
Keyword(s):  
Density Functional ◽  
Theoretical Calculations ◽  
Population Analysis ◽  
Diffraction Method ◽  
Dft Method ◽  
Basis Set ◽  
X Ray Diffraction ◽  
Mulliken Population ◽  
Charge Delocalization ◽  
X Ray

(E)-4-bromo-5-methoxy-2-((o-tolylimino)methyl)phenol was investigated by experimental and theoretical methodologies. The solid state molecular structure was determined by X-ray diffraction method. All theoretical calculations were performed by density functional theory (DFT) method by using B3LYP/6-31G(d,p) basis set. The titled compound showed the preference of enol form, as supported by X-ray diffraction method. The geometric and molecular properties were compaired for both enol-imine and keto-amine forms for title compound. Stability of the molecule arises from hyperconjugative interactions, charge delocalization and intramolecular hydrogen bond has been analyzed using natural bond orbital (NBO) analysis. Mulliken population method and natural population analysis (NPA) have been studied. Also, condensed Fukui function and relative nucleophilicity indices calculated from charges obtained with orbital charge calculation methods (NPA). Molecular electrostatic potential (MEP) and non linear optical (NLO) properties are also examined.

scholarly journals Quantum chemical investigation of spectroscopic, electronic and NLO properties of (1E, 4E)-1-(3-nitrophenyl)-5-phenylpenta-1,4-dien-3-one

2018 ◽  
Vol 6 (1) ◽  
pp. 121
Author(s):  
N Benhalima ◽  
S Yahiaoui ◽  
N Boubegra ◽  
M Boulakoud ◽  
Y Megrouss ◽  
...  
Keyword(s):  
Title Compound ◽  
Population Analysis ◽  
Energy Levels ◽  
Visible Spectrum ◽  
Molecular Geometry ◽  
Dft Method ◽  
Nbo Analysis ◽  
Basis Set ◽  
Vibrational Assignments ◽  
Reactivity Descriptors

In the present work the optimized molecular geometry and harmonic vibrational frequencies of chalcone derivative were calculated by DFT/B3LYP method with 6–31G (d,p) basis set. The vibrational assignments were performed on the basis of the potential energy dis-tribution (PED) of the vibrational modes. Natural bond orbital (NBO) analysis has been performed on title compound using B3LYP/6–31G (d,p) and HSEh1PBE /6–31G (d,p) levels in order to elucidate intermolecular hydrogen bonding, intermolecular charge transfer (ICT) and delocalization of electron density. Mulliken atomic charges, natural population analysis (NPA) and atomic polar tensors (APT) were performed. The nonlinear optical properties of the title compound are also calculated and discussed. Molecular electrostatic poten-tial and HOMO-LUMO energy levels are also computed. Ultraviolet–visible spectrum of the title compound has been calculated using TD–DFT method. The molecular orbital contributions were studied by density of states (DOSs). Global reactivity descriptors have been calculated using the HOMO and LUMO to predict compound reactivity.   

scholarly journals Theoretical calculation of influence of halogen at-oms (F, Cl, Br, I) on arylazopyridine (Azpy) ruthenium complexes behaving as photo sensitizers by DFT method

2018 ◽  
Vol 6 (1) ◽  
pp. 67
Author(s):  
N'guessan Kouakou Nobel ◽  
Ouattara Wawohinlin Patrice ◽  
Bamba Kafoumba ◽  
Ziao Nahossé
Keyword(s):  
Theoretical Calculation ◽  
Fluorine Atom ◽  
Ruthenium Complex ◽  
Ruthenium Complexes ◽  
Dft Method ◽  
Frontier Orbital ◽  
Gap Energy ◽  
Active Isomer ◽  
Least Energy

Photosensivity prediction of several azopyridine ruthenium complexes by DFT and TDDFT methods was performed. g-RuX2 (Azpy) 2 and d-RuX2(Azpy)2 where X stands for F, Cl, Br and I were studied todetermine their activities when halide atoms shift. So, frontier orbital, NBO, NLMO and MLCT transitions as well as an excited lifetime of those complexes was determined. The main difference between them stems from both the electronegativity of the halide atoms and the structure of each complex. Hence, the rank of halide's electronegativity that is as followscp(F)>cp (Cl)>cp (Br)>cp (I) has been discovered to influence all the reactivity of the complexes regardless their structure. Herein, the comparison with the gap energy shows that the most reactive complexes are those with fluorine atom. Especially, d-RuF2(Azpy)2 was admitted to be the most active isomer. Moreover, NBO calculation discloses that the complex becomes less ionic when the electronegativity decreases from F to I atoms. Furthermore, the calculation of NLMO orbitals shows that the bonding Ru-X are very strong. However, this strength decreases also from F to I and the nature of the bonding move from ionic to metallic. Moreover, the bonding from Npy and N2 with Ru are known to be the same confirming the bidentate state of Azpy ligand. Regarding the electronic prediction, the eight complexes are surely assumed to display MLCT transitions that originate the photosensitivity. However, the complex that requires the least energy remains d-RuF2(Azpy)2. This result was also determined by analyzing the excited lifetime that is the ability for a complex to longer linger in the cationic state. At last, we found out that with iodine atoms, the azopyridine ruthenium complex cannot behave as photosensitize dye insofar as I atom hides the main orbitals from Ru regardless the symmetry.

A Computational Study on Structural and Electronic Properties of 1-(4-Chlorophenyl)-2-{[5-(4-Chlorophenyl)-1,2,3-Oxadiazol-2-Yl]Sulfanyl}Ethanone

2019 ◽  
Vol 892 ◽  
pp. 1-7
Author(s):  
Pek Lan Toh ◽  
Montha Meepripruk ◽  
Rosfayanti Rasmidi
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Molecular System ◽  
Population Analysis ◽  
Atomic Charge ◽  
Dft Method ◽  
Basis Sets ◽  
Hydrogen Atoms ◽  
Mulliken Population ◽  
Total Energies

In this paper, a first principle Density Functional Theory (DFT) method was conducted to study the geometric and electronic structures of 1-(4-chlorophenyl)-2-{[5-(4-chlorophenyl) -1,3,4-oxadiazol-2-yl] sulfanyl} ethanone, C16H10Cl2N2O2S. Using B3LYP level of theory with four basis sets of 6-31G**, 6-31++G**, 6-311G**, and 6-311++G**, the equilibrium structure of the title molecule was used to determine the total energies, Frontier molecular orbital’s energies, Mulliken atomic charges, and others. The computed findings present that four total energies obtained are close to each other, with the corresponding values of-59716.06 eV, -59709.42 eV, -59708.56 eV, and-59716.51 eV, respectively for B3LYP/6-31G**, B3LYP/6-31++G**, B3LYP/6-311G**, and B3LYP/6-311++G** methods. The calculated HOMO-LUMO energy gaps were predicted in the range of 4.001 eV - 4.089 eV. In this study, the atomic charge values of molecular system were also determined using Mulliken Population Analysis (MPA) approach. For DFT/B3LYP/6-311G** level of calculation, the computed results show that the atom of C8 accommodates the highest negative charge in the title molecular system. All the oxygen, nitrogen, and chloride atoms are having negative charges, whereas all the hydrogen atoms are having positive charges. In addition, the dipole moment value was also determined to be 1.4758 Debye by employing DFT/B3LYP/6-311G** level of theory.

scholarly journals A Theoretical Study of 5-methyl-2-isopropylphenol (Thymol) by DFT

2021 ◽  
pp. 812-830
Author(s):  
Raksha Gupta
Keyword(s):  
Population Analysis ◽  
Dft Method ◽  
Geometric Optimization ◽  
Oscillator Strengths ◽  
Basis Set ◽  
Excitation Energies ◽  
Mulliken Population ◽  
Visible Absorption ◽  
Vertical Excitation ◽  
Td Dft

Gaussian 09, RevisionA.01, software package was used for the theoretical quantum chemical calculations of 5-methyl-2-isopropylphenol. DFT/B3LYP/6-311G (d, p) basis was used to perform geometric optimization and vibrational frequency determination of the molecule. The statistical thermochemical calculations of the molecule were done at DFT/B3LYP/6-311G (d, p) basis set to calculate the standard thermodynamic functions: heat capacity (CV), entropy (S) and Enthalpy (E). Various NLO properties like total dipole moment (µ), mean linear polarizability (α), anisotropic polarizability (Δα), first order polarizability (β), and second order hyperpolarizability (γ) in terms of x, y, z components were calculated at DFT/B3LYP/6-311G (d, p) basis set for 5-methyl-2-isopropylphenol. Mulliken population analysis was also done using the same basis set. Time Dependent DFT (TD-DFT) method using the same basis set was used to compute UV-Visible absorption spectra, ECD spectra, electronic transitions, vertical excitation energies and oscillator strengths of 5-methyl-2-isopropylphenol.FMO analysis, ESP study were also done using the same basis set.

Theoretical study of metallasilatranes; Bonding nature and prediction of new metallasilatrane

2011 ◽  
Vol 76 (5) ◽  
pp. 619-629 ◽  
Author(s):  
Shigeyoshi Sakaki ◽  
Daisuke Kawai ◽  
Shinya Tsukamoto
Keyword(s):  
Charge Transfer ◽  
Dft Calculation ◽  
Theoretical Study ◽  
Population Analysis ◽  
Dft Method ◽  
Basis Sets ◽  
Equilibrium Geometry ◽  
Polarization Function ◽  
Species Population ◽  
Polarization Functions

The new bond between Pt atom and hypervalent six-coordinate Si species in platinum-silatrane reported recently was theoretically investigated mainly with DFT method and in part with MP2 method. The DFT method with B3PW91 and M06 functionals reproduces well the Pt–Si, Pt–Cl and Si–N bond distances. Though the Si–Cl distance is overestimated by all functionals employed here when one d polarization function is added to each of Si and Cl, the M06-optimized Si–Cl distance is close to the experimental value when two d polarization functions are added to each of Si and Cl, suggesting that the functional and basis sets must be carefully employed in theoretical calculation of hypervalnet six-coordinate Si species. Population analysis clearly indicates that the Pt–Si bond is formed by the charge-transfer (CT) from the occupied dσ orbital of Pt to the empty p orbital of Si, which enhances the CT from the S atoms and Cl ligand to the Pt center. Besides platinum- and palladium-silatranes, no metallasilatrane has been reported so far. Based on the knowledge of bonding nature, we presented theoretical prediction that iridium(I) can form a similar metallasilatrane. Actually, the DFT calculation indicates that iridium-silatrane has essentially the same equilibrium geometry and bonding nature as those of platinum-silatrane.

INFLUENCE OF CATION-HETEROATOM (Li+, Na+, AND K+) INTERACTION ON THE STRUCTURAL AND THERMOCHEMICAL PROPERTIES OF 2′-DEOXYTHYMIDINE NUCLEOSIDE: QTAIM AND NBO ANALYZES

2013 ◽  
Vol 12 (02) ◽  
pp. 1250113 ◽  
Author(s):  
MEHDI SHAKOURIAN-FARD ◽  
ALIREZA FATTAHI
Keyword(s):  
Metal Ion ◽  
Density Functional ◽  
Natural Bond Orbital ◽  
Population Analysis ◽  
Dft Method ◽  
Closed Shell ◽  
Nbo Analysis ◽  
Basis Set ◽  
Functional Theory ◽  
Sugar Ring

Density functional theory (DFT) method and B3LYP/6-311++G(d,p) basis set were used to determine coordination geometries, binding strength, and metal ion affinity (MIA) for interaction of 2′-deoxythymidine (dT) with alkali metal cations including Li+, Na+ , and K+ . Calculations demonstrated that the interaction of dT with these cations is tri-coordinated η (O2, O4′, O5′). Among these cations, Li+ cation exhibited the most tendency for interaction with dT. Cations via their interaction with dT can affect the N-glycosidic bond length, the values of pseudorotation of the sugar ring, the orientation of base unit with respect to sugar ring and the acidity of O5′H, O3′H, and N3H groups in 2′-dT nucleoside. Natural bond orbital (NBO) analysis was performed to calculate the charge transfer and natural population analysis of the complexes. Quantum theory of atoms in molecules (QTAIM) was also applied to determine the nature of interactions. It was shown that in these complexes, (dT- Li+ , dT- Na+ , and dT- K+ ), the bonds are an electrostatic (closed-shell) interaction in the nature.

Automated 3-D cell population analysis in thick tissue sections using laser-scanning confocal-microscopy data

1993 ◽  
Vol 51 ◽  
pp. 562-563
Author(s):  
Hakan Ancin
Keyword(s):  
Laser Scanning ◽  
Population Analysis ◽  
Three Dimensional ◽  
Large Data ◽  
Laser Scanning Confocal Microscopy ◽  
Tissue Slices ◽  
Scanning Confocal Microscopy ◽  
Tissue Sections ◽  
Spatially Adaptive ◽  
Microscopy Data

This paper presents methods for performing detailed quantitative automated three dimensional (3-D) analysis of cell populations in thick tissue sections while preserving the relative 3-D locations of cells. Specifically, the method disambiguates overlapping clusters of cells, and accurately measures the volume, 3-D location, and shape parameters for each cell. Finally, the entire population of cells is analyzed to detect patterns and groupings with respect to various combinations of cell properties. All of the above is accomplished with zero subjective bias.In this method, a laser-scanning confocal light microscope (LSCM) is used to collect optical sections through the entire thickness (100 - 500μm) of fluorescently-labelled tissue slices. The acquired stack of optical slices is first subjected to axial deblurring using the expectation maximization (EM) algorithm. The resulting isotropic 3-D image is segmented using a spatially-adaptive Poisson based image segmentation algorithm with region-dependent smoothing parameters. Extracting the voxels that were labelled as "foreground" into an active voxel data structure results in a large data reduction.

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