Theoretical investigation on the geometric, spectroscopic, nonlinear optical parameter, and frontier molecular orbital of 1,3-bis(4-methoxyphenyl)prop-2-en-1-one by DFT/ab initio calculations

2013 ◽  
Vol 91 (12) ◽  
pp. 1225-1232 ◽  
Author(s):  
Xiao-Hong Li ◽  
Rui-Zhou Zhang ◽  
Xian-Zhou Zhang
Keyword(s):  
Ab Initio ◽  
Title Compound ◽  
Density Functional ◽  
Nonlinear Optical ◽  
Optical Parameter ◽  
Basis Set ◽  
Frontier Molecular Orbital ◽  
Chemical Hardness ◽  
Hartree Fock ◽  
The Difference

Quantum chemical calculations of energies, geometries, and vibrational wavenumbers of 1,3-bis(4-methoxyphenyl)prop-2-en-1-one (C17H16O3) in the ground state were carried out by the using ab initio Hartree−Fock and density functional theory (DFT/B3LYP) methods with the 6-311++G** basis set. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. Theoretical vibrational spectra of the title compound were interpreted by means of potential energies distributions. The theoretical spectrograms for IR spectra of the title compound have been constructed. The analysis of natural bond orbitals shows that the intramolecular hyperconjugative interactions are formed by the orbital overlap between π*(C–C) and π(C–C) bond orbitals, which results in intramolecular charge transfer causing stabilization of the system. The predicted nonlinear optical properties of the title compound are much larger than those of urea. In addition, the analysis of frontier molecular orbitals shows that the title compound has good stability and high chemical hardness.

scholarly journals Theoretical Study of Solvent Effects on the Electronic and Thermodynamic Properties of Tetrathiafulvalene (TTF) Molecule Based on DFT

2021 ◽  
pp. 42-54
Author(s):  
Rabiu Nuhu Muhammad ◽  
N. M. Mahraz ◽  
A. S Gidado ◽  
A. Musa
Keyword(s):  
Thermodynamic Properties ◽  
Bond Length ◽  
Density Functional ◽  
Theoretical Study ◽  
Energy Gap ◽  
Basis Set ◽  
Basis Sets ◽  
Frontier Molecular Orbital ◽  
Orbital Energy ◽  
Chemical Hardness

Tetrathiafulvalene () is an organosulfur compound used in the production of molecular devices such as switches, sensors, nonlinear optical devices and rectifiers. In this work, a theoretical study on the effects of solvent on TTF molecule was investigated and reported based on Density Functional Theory (DFT) as implemented in Gaussian 03 package using B3LYP/6-31++G(d,p) basis set. Different solvents were introduced as a bridge to investigate their effects on the electronic structure. The HUMO, LUMO, energy gap, global chemical index, thermodynamic properties, NLO and DOS analysis of the TTF molecule in order to determine the reactivity and stability of the molecule were obtained. The results obtained showed that the solvents have effects on the electronic and non-linear-optical properties of the molecule. The optimized bond length revealed that the molecule has strong bond in gas phase with smallest bond length of about 1.0834Å than in the rest of the solvents. It was observed that the molecule is more stable in acetonitrile with HOMO-LUMO gap and chemical hardness of 3.6373eV and 1.8187eV respectively. This indicates that the energy gap and chemical hardness of TTF molecule increases with the increase in polarity and dielectric constant of the solvents. The computed results agreed with the results in the literature. The thermodynamics and NLO properties calculation also indicated that TTF molecule has highest value of specific heat capacity (Cv), total dipole moment () and first order hyperpolarizability () in acetonitrile, while acetone has the highest value of entropy and toluene has a slightly higher value of zero point vibrational energy (ZPVE) than the rest of the solvents. The results show that careful selection of the solvents and basis sets can tune the frontier molecular orbital energy gap of the molecule and can be used for molecular device applications.

Conformational and Vibrational Analysis of 2,4-, 2,5- and 2,6-Difluorobenzaldehydes by ab initio Hartree-Fock and Density Functional Theory Calculations

2008 ◽  
Vol 63 (3-4) ◽  
pp. 175-182 ◽  
Author(s):  
Adnan Sağlam ◽  
Fatih Ucun
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Vibrational Analysis ◽  
Molecular Structures ◽  
Basis Set ◽  
Functional Theory ◽  
Vibrational Assignments ◽  
Hartree Fock ◽  
The Mean

The optimized molecular structures, vibrational frequencies and corresponding vibrational assignments of the two planar O-cis and O-trans rotomers of 2,4-, 2,5- and 2,6-difluorobenzaldehyde have been calculated using ab initio Hartree-Fock (HF) and density functional theory (B3LYP) methods with the 6-311++G(d,p) basis set level. The calculations were adapted to the CS symmetries of all the molecules. The O-trans rotomers with lower energy of all the compounds have been found as preferential rotomers in the ground state. The mean vibrational deviations between the vibrational frequency values of the two conformers of all the compounds have been shown to increase while the relative energies increase, and so it has been concluded that the higher the relative energy between the two conformers the bigger is the mean vibrational deviation.

Recent Advances in ab initio time—dependent Hartree-Fock theory and their applications to predict nonlinear optical properties of semiconductor nanoclusters

1999 ◽  
Vol 579 ◽  
Author(s):  
Shashi P. Karna ◽  
Prakashan P. Korambath
Keyword(s):  
Ab Initio ◽  
Nonlinear Optical ◽  
Time Dependent ◽  
Basis Set ◽  
Order Effects ◽  
Hartree Fock ◽  
Nlo Property ◽  
Nlo Materials ◽  
A Charge ◽  
Hf Calculations

ABSTRACTRecent advancements in ab initio time-dependent Hartree-Fock (TDHF) theory have made it a technique of choice for modeling nanoscale nonlinear optical (NLO) materials from first-principles. We have used this method to study structure-NLO property relationships of GaN, GaP and GaAs clusters. The geometry of the clusters used in the study was optimized by ab initio Hartree Fock (HF) calculations with the use of even tempered Gaussian (ETG) basis set. The clusters used in this study are of the type Gam Xn (M = 1,3,4,7 and n = 1,3,4,7) where X=N, P, and As. The GamXn clusters are in a charge neutral (q = 0) state for m = n and in appropriately charged state for m ∦ n. The magnitude of the calculated (hyper)polarizabilities appears to strongly depend on the composition of the cluster. For the same composition of heteroatoms, the hyperpolarizability depends on the size as well as the geometry of the cluster. The cluster size-dependence of calculated (hyper)polarizabilities is more pronounced for the first-hyperpolarizability. β than for the polarizability, α The calculated β(–ωμ,ωl,ω2) corresponding to various second order effects shows the following trend β(–2ω; ω,ω) > β(–ω; 0, ω) >β(0;0,0).

scholarly journals Molecular modelling, spectroscopic characterization and nonlinear optical analysis on N-Acetyl-DL-methionine

2020 ◽  
Vol 66 (6 Nov-Dec) ◽  
pp. 749
Author(s):  
N. Günay ◽  
Ö. Tamer ◽  
D. Avcı ◽  
E. Tarcan ◽  
Y. Atalay
Keyword(s):  
Electronic Properties ◽  
Title Compound ◽  
Density Functional ◽  
Nonlinear Optical ◽  
Energy Gap ◽  
Spectroscopic Characterization ◽  
Oscillator Strengths ◽  
Basis Set ◽  
Molecular Electrostatic Potential Surface ◽  
Experimental Values

In this present methodical study, on the basis of the density functional theory (DFT), the first-principles calculations have been employed successfully to study the structural and electronic properties of N-acetyl-DL-methionine (C7H13NO3S) which is a derivative of DL-methionine which is also known DL-2-amino-4-methyl-thiobutanoic acid. Optimized molecular structure, vibrational frequencies and also 13C and 1H NMR chemical shift values of the title compound are provided in a detailed manner by using B3LYP and HSEH1PBE functionals by applying 6-311++G(d,p) basis set for calculations using Gaussian 09W program. The comparison of the calculated values with the experimental values provides important information about the title compound. In addition, the electronic properties (UV-Vis calculations) of the title compound, such as HOMO-LUMO energy values and energy gap, absorption wavelengths, oscillator strengths were performed basing on the optimized structure in gas phase. Moreover, the molecular electrostatic potential surface, dipole moment, nonlinear optical properties, linear polarizabilities and first hyperpolarizabilities and chemical parameters have also been studied.

scholarly journals Xrd, Quantum Chemical, Vibrational, Thermal and Antifungal Activity Analysis on 3-Nitroanilinium Hydrogen Oxalate

2019 ◽  
Vol 9 (1S3) ◽  
pp. 319-323
Keyword(s):  
Density Functional ◽  
Density Functional Method ◽  
Functional Method ◽  
Basis Set ◽  
Frontier Molecular Orbital ◽  
Geometrical Parameters ◽  
Vibrational Assignments ◽  
Hartree Fock ◽  
Homo Lumo ◽  
Good Agreement

3-nitroanilinium hydrogen oxalate has been crystallized successfully by solvent evaporation method. Optimized molecular geometrical parameters and the vibrational assignments of 3NAOX has been calculated by using Hartree-Fock (HF) and density functional method (B3LYP) with 6-311++G (d, p) basis set. The computational analysis showed good agreement with the experimental data. The energy and various parameters were obtained by HOMO–LUMO plot. The apparent pharmaceutical/biological activity of the salt confirmed by lower band gap value obtain from the Frontier Molecular Orbital (FMO) analysis. Thermal properties of 3NAOX were analyzed by TGA/DTA. The grown crystals were involved in an antimicrobial activity against certain potentially threatening microbes which shows that grown crystal screened the bacteria.

scholarly journals Structural, Vibrational, Quantum Chemical Calculations, Thermal and Antimicrobial Studies On Nitrate Salt Of 3-Nitroaniline

2021 ◽  
Author(s):  
Thangarasu S ◽  
Siva V ◽  
Asath Bahadur S ◽  
Athimoolam S
Keyword(s):  
Density Functional ◽  
Basis Set ◽  
Experimental Result ◽  
Frontier Molecular Orbital ◽  
Geometrical Parameters ◽  
Functional Theory ◽  
Hartree Fock ◽  
Antimicrobial Studies ◽  
Evaporation Technique ◽  
Homo Lumo

Abstract In this work, 3-nitroanilinium nitrate (3NAN) has been synthesized and crystallized successfully by solution growth combined with solvent evaporation technique. 3NAN molecular structure has been optimized with Density Functional Theory (DFT) using B3LYP function and Hartree-Fock method with a 6-311 + + G(d,p) basis set. The geometrical parameters of the title molecules have been analyzed. The computed vibrational spectra were compared with experimental result which show appreciable agreement. Thermal stability of the crystal was analyzed with TGA/DTA and the melting points of the salt identified at 209 ºC. HOMO-LUMO energy calculations have shown the charge transfer within the molecu le. The possible pharmaceutical/biological activity of the salts confirmed by the Frontier Molecular Orbital (FMO) analysis have lower band gap value. The antimicrobial activity of grown crystals were tested against certain potentially threatening microbes.

DFT QUANTUM CHEMICAL STUDIES ON 1-[N-(2-PYRİDYL) AMİNOMETHYLİDENE]-2(1H)-NAPHTALENONE

2012 ◽  
Vol 11 (04) ◽  
pp. 745-762 ◽  
Author(s):  
MEHMET TOY ◽  
HASAN TANAK
Keyword(s):  
Title Compound ◽  
Quantum Chemical ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Formation Enthalpy ◽  
Polarizable Continuum Model ◽  
Second Order ◽  
Basis Set ◽  
Frontier Molecular Orbital ◽  
Statistical Thermodynamic

Quantum chemical calculations of the structure, molecular electrostatic potential and thermodynamic functions have been performed using the density functional (DFT/B3LYP) method with the 6-311++G(d,p) basis set for the title compound 1-[N-(2-pyridyl)aminomethylidene}-2(1H)-Naphtalenone. The energetic behavior of the title compound in solvent media has been examined by applying the Onsager and the polarizable continuum model. To investigate second order nonlinear optical properties of the title compound, the electric dipole μ, the polarizability α and the first hyperpolarizability β were computed using the density functional B3LYP and CAM-B3LYP methods with the 6-311++G(d,p) basis set. According to our calculations, the title compound exhibits nonzero β value revealing second order NLO behavior. The changes of thermodynamic properties for the formation of the title compound with the temperature ranging from 200 K to 500 K have been obtained using the statistical thermodynamic method. The relationship between formation enthalpy and entropy changes has been investigated with the entropy–enthalpy compensation. Besides, natural bond orbital and frontier molecular orbital analysis of the title compound were investigated by theoretical calculations.

Ab initio MO Optimizations of Osmiumtetracarbonyldihydride and Metallacyclophanes with two Osmium Atoms and their Molecular Complexes with Different Guests

1998 ◽  
Vol 53 (10) ◽  
pp. 1223-1235
Author(s):  
Inge Warttmann ◽  
Günter Häfelinger
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Cyano Group ◽  
Single Point ◽  
Molecular Complexes ◽  
Basis Set ◽  
Basis Sets ◽  
Basis Set Superposition Error ◽  
Hartree Fock ◽  
Surprising Effect

AbstractAb initio Hartree-Fock (HF) and density functional (DFT) optimizations on the test m olecule osmiumtetracarbonyldihydride (13) with various basis sets show that the lanl2mb pseudopotential basis set for osmium leads in the HF approximation to more reliable molecular geometries than the DFT calculations. This HF procedure was used for the optimizations of molecular geometries of three isomeric 4,4,4,4,17,17,17,17-octacarbonyl-4,17-diosma[7.7]ortho-, meta- and paracyclophanes 1 to 3, of which 3 was found to be predestined for formation of various host-guest complexes with possible guests benzene (4), fluorobenzene (5), 1,3,5- trifluorobenzene (6), 1,2,4,5-tetrafluorobenzene (7), hexafluorobenzene (8), fluoroanil (9), tetrafluoroethene (10), tetracyanoethene (11) and aniline (12). Results of optimized hostguest geometries are presented graphically for inclusions and associations of guest 4 to 12 with 3. Calculated lanl2mb interaction energies, after correction for basis set superposition error (BSSE), remain favourable only for inclusion of 5 and associations of 5, 10, 11 and 12. Additionally lanl2dz single point calculations for inclusion, which may not need BSSE correction because of the improved basis set, are favourable for 6 and 12. According to lanl2mb HOMO and LUMO energies, 3 may as well easily donate or accept electrons. This may be an interpretation to the surprising effect, that Mulliken total charges are positive on the electron accepting guest molecules 4 to 11. There are geometrical peculiarities in the optimized host-guest complexes for inclusion and association. Fluorine atoms of 5 to 10 and nitrogen atoms of a cyano group of 11 and the amino group of 12 like to come close to one or two carbonyl groups. Similar distances of 2.70 Å to 3.57 Å between the O atom of the carbonyl group and the F atom or N atom appear in all optimizations of inclusion and association of 5 to 12 except in the case of association of tetrafluoroethene (10).

Calculations of Atomic and Electronic Structure for (100) Surfaces of SrTiO3 Perovskite

2002 ◽  
Vol 718 ◽  
Author(s):  
R. I. Eglitis ◽  
E. Heifets ◽  
E. A. Kotomin ◽  
G. Borstel
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Computer Code ◽  
Basis Set ◽  
Surface Relaxation ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Hartree Fock ◽  
Atomic And Electronic Structure

AbstractWe present and discuss main results of the calculations for the surface relaxation and rumpling of SrTiO3 surfaces with TiO2 and SrO terminations using a wide variety of methods of modern computational physics and chemistry, including the shell model (SM) and ab initio methods based on Hartree-Fock (HF) and Density Functional Theory (DFT). The HF and DFT formalisms with different exchange-correlation functionals are implemented into Crystal-98 computer code using a Gaussian-type basis set. We demonstrate that a hybrid B3PW formalism gives the best results for the bulk SrTiO3 properties. Results are compared with previous ab initio plane-wave LDA calculations and LEED experiments. Our calculations demonstrate an increase of the covalency effects between Ti and O atoms near the surface.

scholarly journals Molecular characterization of yohimbine hydrochloride using vibrational spectroscopy and quantum chemical calculations

BIBECHANA ◽  
2012 ◽  
Vol 8 ◽  
pp. 73-80 ◽  
Author(s):  
Bhawani Datt Joshi ◽  
Poonam Tandon ◽  
Sudha Jain
Keyword(s):  
Ab Initio ◽  
Vibrational Spectroscopy ◽  
Density Functional ◽  
Basis Set ◽  
Energy Potential ◽  
Vibrational Assignments ◽  
Hartree Fock ◽  
B3lyp Method ◽  
Proper Scaling

In this work, we have performed the extraction of yohimbine hydrochloride (C21H27ClN2O3) (YHCl). The optimized geometry, total energy, potential energy surface and vibrational wavenumbers of YHCl have been determined by using ab initio Hartree–Fock (HF) and density functional theory (DFT/B3LYP) method with 6-311++G(d,p) basis set. The calculated wavenumbers are scaled by a proper scaling factor. A selected number of vibrational assignments are provided for the observed Raman and IR spectra. Keywords: YHCl; vibrational spectroscopy; ESP; ab initio and DFT calculationsDOI: http://dx.doi.org/10.3126/bibechana.v8i0.4923   BIBECHANA 8 (2012) 73-80

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