scholarly journals A Preliminary First Principle Study on Photochromism of Diarylethene Molecules

2019 ◽  
Vol 1 ◽  
pp. 67-77
Author(s):  
Ravi Karki
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Energy Difference ◽  
Basis Set ◽  
Functional Theory ◽  
Solvation State ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital ◽  
Energy Consideration ◽  
Hybrid Density Functional

Photochromism in some diarylethene molecules have been studied by using hybrid density functional theory using the ground state energy consideration. In particular, B3LYP functional and all electron basis set 6-311G (2d,2p) as implemented in Gaussian09 suites of program has been used to investigate the energy difference of two stable isomers of stilbene, azobenzene, cyclooctane, and 1,2, dimethylcyclohexane molecules. The energy difference is corroborated to calculate the frequencies of photons that are required to induce photochromism in these molecules in vacuum and in solvation state. The study found that the molecules exhibit photochromism at various frequency range from infra-red to ultraviolet. The binding energy per atom, charge distribution, HOMO-LUMO (Highest Occupied Molecular Orbital and Lowest Unoccupied Molecular Orbital) gap are also calculated for all the molecules in vacuum, water and ethanol solvent. The results obtained are in accordance with the experimental observations.

scholarly journals EDTA as a corrosion inhibitor for Al in 0.5 M HCl: adsorption, thermodynamic and theoretical study

2016 ◽  
Vol 6 (3) ◽  
pp. 235 ◽  
Author(s):  
Rehab Ebaid Azooz
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Inhibition Efficiency ◽  
Energy Difference ◽  
Basis Set ◽  
Stable Complex ◽  
Adsorption Parameters ◽  
Functional Theory ◽  
Highest Occupied Molecular Orbital ◽  
Unstable Complex

<p class="Default"><span lang="EN-US">In this study; EDTA is used in very small amount (10<sup>-10</sup> M) as an inhibitor for the Al corrosion in 0.5 M HCl. Thermodynamic and adsorption parameters are calculated. The result shows that, in this range of concentrations, EDTA is chemisorbed at the Al surface, forming a stable complex with Al and give inhibition efficiency up to 89 %. For more con­centration, unstable complex is formed and acceleration of corrosion occurs. The adsorp­tion fit well to Langmuir, Temkin isotherms and El-awady model. Density functional theory (DFT) is used to study the geometrical optimizations of EDTA. From the obtained optimized structure, The highest occupied molecular orbital (EHOMO), the lowest unoc­cupied molecular orbital (ELUMO and their energy difference (ΔE), the total energy (TE), electronegativity (χ), dipole moment (µ), global hardness (η), global softness (σ), elec­tron affinity (A), ionization potential (I), the fraction of electrons transferred (∆N) and were determined using B3LYP/6-31G(d,p) basis set.</span></p>

Structural, QTAIM, thermodynamic properties, bonding, aromaticity and NMR analyses of cation–π interactions of mono and divalent metal cations (Li+, Na+, K+, Be2+, Mg2+, and Ca2+) with substituted pyrazine derivatives

2015 ◽  
Vol 14 (06) ◽  
pp. 1550044 ◽  
Author(s):  
Maryam Zaboli ◽  
Heidar Raissi
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Chemical Potential ◽  
Basis Set ◽  
Chemical Hardness ◽  
Aromatic Rings ◽  
Functional Theory ◽  
Highest Occupied Molecular Orbital ◽  
Polarized Continuum Model ◽  
Lowest Unoccupied Molecular Orbital

Theoretical investigation of 42 cation-π complexes formed by the alkali metal ( Li +, Na +, K +), alkaline-earth cations ( Be 2+, Mg 2+, Ca 2+) and π-system of the pyrazine and its derivatives have been performed at density functional theory (DFT) (B3LYP functional) and MP2 methods with 6-311++G** basis set in the gas phase and the polarized continuum model (PCM)-water solvation. The following substituents have been taken into consideration: Br , Cl , CH 3, OH , OCH 3 and SH . The interactions present in these complexes have been investigated by means of the natural bond orbital (NBO) and the Bader's quantum theory of atoms in molecules (QTAIMs) approaches. The effects of the interactions on NMR data have been probed using the GIAO-based method to extend investigation of the studied compounds. The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies show that charge transfer occurs within each complex. Vibrational frequencies and physical properties such as dipole moment, chemical potential, chemical hardness and chemical electrophilicity of these compounds have been systematically explored. The aromaticity of aromatic rings has been measured using several well-established indices of aromaticity such as nucleus-independent chemical shift, harmonic oscillator models of the aromaticity, para-delocalization index, average two-center indices, aromatic fluctuation index and π-fluctuation aromatic index.

scholarly journals Case Study in a Conceptual DFT Investigation of New Corrosion Inhibitor

2021 ◽  
Vol 11 (4) ◽  
pp. 4007-4015
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Basis Set ◽  
Functional Theory ◽  
Dft Modeling ◽  
Highest Occupied Molecular Orbital ◽  
The Density Functional Theory ◽  
Modeling Techniques ◽  
Lowest Unoccupied Molecular Orbital

Inhibition efficiency of thiosemicarbazide derivative, namely 4-ethyl-1-(4-oxo-4-phenylbutanoyl)thiosemicarbazide (EOPT) on corrosion of mild steel, was investigated utilizing the density functional theory (DFT) modeling techniques in the aqueous phase. Chemical parameters at the quantum level, such as energies of highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), dipole moment (µ), absolute electronegativity (χ), global hardness (η), softness (σ), and the fraction of electrons transferred (∆N) have been determined at the B3LYP level of theory with 6-31G (d, p) basis set.

Complete basis set, hybrid-density functional theory study, and natural bond orbital interpretations of the conformational behavior of halocarbonyl, thiocarbonyl, and selenocarbonyl isocyanates

2012 ◽  
Vol 90 (4) ◽  
pp. 333-343 ◽  
Author(s):  
Seiedeh Negar Mousavi ◽  
Davood Nori-Shargh ◽  
Hooriye Yahyaei ◽  
Kobra Mazrae Frahani
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Energy Difference ◽  
Basis Set ◽  
Hybrid Density Functional Theory ◽  
Total Dipole Moment ◽  
Functional Theory ◽  
Complete Basis Set ◽  
Conformation Stability ◽  
Hybrid Density Functional

Complete basis set CBS-QB3, hybrid-density functional theory (B3LYP/Def2-TZVPP) based methods and NBO interpretation were used to investigate the impacts of the stereoelectronic effects and electrostatic and steric interactions on the conformational properties of halocarbonyl isocyanates (halo = F (1), Cl (2), and Br (3)), halothiocarbonyl isocyanates (halo = F (4), Cl (5), and Br (6)), and haloselenocarbonyl isocyanates(halo = F (7), Cl (8), and Br (9)). Both methods showed that the Z-conformations of compounds 1, 4, and 7 are more stable than their corresponding E conformations, but the stability of the E conformations, when compared with the corresponding Z conformations, increases from compound 1 to compound 3, compound 4 to compound 6, and also from compound 7 to compound 9. The NBO analysis showed that the generalized anomeric effect (GAE) is in favor of the Z conformations of compounds 1, 4, and 7. The GAE values calculated (i.e., GAEE–GAEZ) increase from compound 1 to compound 3, compound 4 to compound 6, and also from compound 7 to compound 9. On the other hand, there are none of the same trends between the calculated total dipole moment and the Gibbs free energy difference values between the E and Z conformations (i.e., ΔμE–Z and ΔGE–Z) of compounds 1–3, 4–6, and 7–9. Accordingly, the GAE succeeds in accounting for the increase of the E conformation stability from compound 1 to compound 3, compound 4 to compound 6, and also from compound 7 to compound 9. Therefore, the GAE associated with the electron delocalization, not the total dipole moment changes (i.e., ΔμE–Z), is a reasonable indicator of the total energy difference in compounds 1–3, 4–6, and 7–9. There is a direct correlation between the calculated GAE and Δ[r2–6(E) – r2–6(Z)] parameters. Importantly, there are interesting through-space electron delocalizations (LP2X6→π*C4–O5) that justify the increase of the E conformation stability from compound 1 to compound 3, compound 4 to compound 6, and also from compound 7 to compound 9, when compared with their corresponding Z conformations. The correlations between the GAE, bond orders, total steric exchange energies (TSEE), ΔGZ–E, ΔμE–Z, structural parameters, and conformational behaviors of compounds 1–9 were investigated.

The Geometric and Electronic Structures of Fen-1Si(n=2-7) Clusters

2010 ◽  
Vol 150-151 ◽  
pp. 984-987
Author(s):  
Shuai Qin Yu ◽  
Li Hua Dong ◽  
Yan Sheng Yin
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Energy Difference ◽  
Ground State Structure ◽  
Magic Numbers ◽  
Highest Occupied Molecular Orbital ◽  
Hybridization Intensity ◽  
Lowest Unoccupied Molecular Orbital ◽  
The Stability

The geometric structures and electronic properties of Si doped Fen (n=2-7) clusters have been systematically studied at the BPW91 level in density-functional theory (DFT). Calculated results show that an Si impurity does not change the ground-state structure of small iron clusters and prefers to occupy surface site bonding with iron atoms as many as possible. The second-order energy difference and the vertical ionization potential show that n=4 and 6 are magic numbers within the size range studied, but the maximum value occurs at n=4 for the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital(LUMO). It is found that the hybridization intensity between Si and Fe atoms is relevant to the stability of clusters.

Cross-conjugation as a Motif for Organic Non-Linear Optical Molecules

2014 ◽  
Vol 1698 ◽  
Author(s):  
Meghana Rawal ◽  
Kerry Garrett ◽  
Andreas F. Tillack ◽  
Werner Kaminsky ◽  
Evgheni Jucov ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Dipole Moments ◽  
X Ray Diffraction ◽  
Conjugated Molecules ◽  
Functional Theory ◽  
Highest Occupied Molecular Orbital ◽  
Donor And Acceptor ◽  
Vis Spectroscopy ◽  
Lowest Unoccupied Molecular Orbital

ABSTRACTWe studied the effect of a cross-conjugated bridging group (χC) on charge-transfer in a push-pull chromophore system. The hyperpolarizability of such molecules was found to be comparable to that of a fully π-conjugated molecule (πC) with the same donor and acceptor. The cross-conjugated moiety was then applied as a pendant to a fully π-conjugated chromophore containing a tricyanopyrroline acceptor (TCP). The addition of a χC moiety did not alter the intrinsic hyperpolarizability and provides an avenue for extending and aiding πC systems. The molecules were examined by X-ray diffraction (XRD), hyper-Raleigh scattering (HRS) and UV-visible (UV-vis) spectroscopy. Experimental results were compared with the predictions of density functional theory (DFT). Cross-conjugated molecules have comparable β values, relative to πC molecules, due to reduced spatial overlap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). Thus, the χC architecture could facilitate independent modification of donor and acceptor strengths while minimizing unfavorable effects on electronic transitions and dipole moments.

scholarly journals Density Functional Theory Study of CL-20/Nitroimidazoles Energetic Cocrystal Compounds in an External Electric Field

2021 ◽  
Author(s):  
xiaosong Xu ◽  
Renfa Zhang ◽  
Wenxin Xia ◽  
Peng Ma ◽  
Congming Ma ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electric Field ◽  
Nitro Group ◽  
External Electric Field ◽  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Functional Theory ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

Abstract The external electric field has a significant influence on the sensitivity of the energetic cocrystal materials. In order to find out the relationship between the external electric field and sensitivity of energetic cocrystal compounds 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane/1,4-dinitroimidazole (CL-20/1,4-DNI), 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane/1-methyl-2,4-dinitro-1H-imidazole (CL-20/2,4-MDNI) and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane/1-methyl-4,5-dinitro-1H-imidazole (CL-20/4,5-MDNI). In this work, density functional theory (DFT) at B3LYP-D3/6-311+G(d,p) and M062X-D3/ma-def2 TZVPP levels was employed to calculate the bond dissociation energies (BDEs) of selected N-NO2 trigger bonds, frontier molecular orbitals, electrostatic potentials (ESPs) and nitro group charges (QNO2) under different external electric field. The results show that as the positive electric field intensity increases, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy gap and BDEs become smaller, and the local positive ESPs becomes larger, so that the energetic cocrystals tends to have higher sensitivity. In addition, the linear fitting results show that the trigger bond length and nitro group charge changes are closely related to the external electric field strength.

scholarly journals Crystal Structure, Hirshfeld Surface and Frontier Molecular Orbital Analyses of N-[2-(trifluoromethyl)phenyl]succinamic Acid

2020 ◽  
Vol 32 (12) ◽  
pp. 3179-3185
Author(s):  
P.A. Suchetan ◽  
S. Naveen ◽  
N.K. Lokanath ◽  
P. Krishna Murthy ◽  
M.V. Deepa Urs
Keyword(s):  
Hydrogen Bonds ◽  
Molecular Orbital ◽  
Density Functional ◽  
Hirshfeld Surface ◽  
Basis Set ◽  
Frontier Molecular Orbital ◽  
Reactivity Descriptors ◽  
Succinamic Acid ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

The ortho-CF3 substituent and the N-H bond are in syn-conformation in N-[2-(trifluoromethyl)phenyl]succinamic acid. In amide and acid functionalities, the carbonyl groups are directed in opposite directions to each other and their related-CH2 groups. syn-Conformation is observed for the acid functionality, where the carbonyl C=O and hydroxyl O-H bonds are directed in the same direction. Three planar fragments comprise of the molecule: aromatic ring (A), core portion -Carm-N(H)-C(=O)-C(H2)-C(H2)(B) and -C(H2)-C(=O)-OH(C). The dihedral angle between a pair of fragments being 48.6(4)º (A and B), 81.6 (4)º (B and C) and 70.5 (5)º (A and C). N-H•••O hydrogen bonds bind the molecules forming C(4) chains in the crystal, and the neighbouring anti-parallel chains are bound by O-H•••O hydrogen bonds resulting in a chair shaped ribbon of one-dimensional nature. The Hirshfeld surface study was carried out, including fingerprint plots. Studies have shown that the interactions with O•••H/H•••O (27.4%), H•••H (27.3%) and H•••F/F•••H (20.2%) substantially added to the surface. Theoretically, the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and various global reactivity descriptors were also computed by the density functional theory (DFT/B3LYP) approach with a 6-311G(d, p) basis set in the ground state on the geometrically optimized structure in the gas phase.

scholarly journals Relationship between the Electrical Characteristics of Molecules and Fast Streamers in Ester Insulation Oil

2020 ◽  
Vol 21 (3) ◽  
pp. 974 ◽  
Author(s):  
Kaizheng Wang ◽  
Feipeng Wang ◽  
Ziyi Lou ◽  
Qiuhuang Han ◽  
Qi Zhao ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Ester Group ◽  
Electrical Characteristics ◽  
Functional Theory ◽  
Highest Occupied Molecular Orbital ◽  
Lightning Impulse ◽  
Lowest Unoccupied Molecular Orbital ◽  
Natural Ester ◽  
Insulation Oil

The effects of C=C, ester and β-H groups on the ionization potential (IP) and electron affinity (EA) of molecules in natural ester insulation oil were investigated by density functional theory (DFT). The major contribution to the highest occupied molecular orbital (HOMO) comes from the carbon atoms adjacent to C=C. Thus, the IPs of triglycerides decrease as the number of C=C double bonds increases. The C=C in alkanes may also lower the IP. However, the β-H in triglycerides has little effect on the IP, and C=C and β-H have only a small effect on the EAs of the triglycerides because of the major contributions of atoms near the ester group in triglycerides to the lowest unoccupied molecular orbital (LUMO). This study calculated the IPs of 53 kinds of molecules in FR3, which are significantly lower compared with those of molecules in mineral oil (MO) and trimethylolpropane triester without C=C. However, the lightning impulse breakdown voltage (LI Vb) of trimethylolpropane triester is still significantly lower than that of MO at the large gap. Therefore, the transition from slow to fast streamers under low lighting impulse voltage is determined by the ester group rather than by C=C and β-H. The ester group may attract more electrons, impacting itself more compared to alkane in MO and facilitating the transition from slow to fast streamers.

scholarly journals Structure, Electronic And Vibrational Study of 7-Methyl-2,3-Dihydro-(1,3)Thiazolo(3,2-A) Pyrimidin-5-One by Using Density Functional Theory

2018 ◽  
Vol 22 (2) ◽  
pp. 1-11
Author(s):  
Bhawani Datt Joshi ◽  
Janga Bahadur Khadka ◽  
Atamram Bhatt
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Density Functional ◽  
Basis Set ◽  
Orbital Energy ◽  
Potential Energy Distribution ◽  
Functional Theory ◽  
Hartree Fock ◽  
Solvent Phase ◽  
Lowest Unoccupied Molecular Orbital

 We have presented molecular structure and vibrational wavenumber assignments of 7-methyl-2,3-dihydro-(1,3)thiazolo(3,2-a)pyrimidin-5-one. Both ab initio Hartree-Fock and density functional theory employing 6-311++G(d,p) basis set have been used for the calculations. The scaled values of the calculated vibrational frequencies were used for assignments on the basis of potential energy distribution. The structure-activity relation has been interpreted by mapping molecular electrostatic potential surface. Electronic properties have been analyzed by using time dependent density functional theory (TD-DFT) for both gaseous and solvent phase. The calculated HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy values show that the charge transfer occurs within the molecule. Journal of Institute of Science and TechnologyVolume 22, Issue 2, January 2018, Page: 1-11 

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