scholarly journals Derivative discontinuity, bandgap and lowest unoccupied molecular orbital in density functional theory

2012 ◽  
Vol 136 (20) ◽  
pp. 204111 ◽  
Author(s):  
Weitao Yang ◽  
Aron J. Cohen ◽  
Paula Mori-Sánchez
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Density Functional ◽  
Functional Theory ◽  
Derivative Discontinuity ◽  
Lowest Unoccupied Molecular Orbital

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 Simulation Study of Structural and Electronic Properties for Adducts complexes of Bis(Acetylacetonato)oxoVandium (IV) with 4-(Para-substituted phenyl)-1,2,3-Selenadiazole

2021 ◽  
Vol 2063 (1) ◽  
pp. 012002
Author(s):  
Dalal H Alsawad ◽  
Ali A Al-Riyahee ◽  
Ali J Hameed
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
Molecular Orbital ◽  
Density Functional ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Lowest Unoccupied Molecular Orbital ◽  
Reorganization Energies ◽  
Cis And Trans ◽  
Optimized Geometries

Abstract A series of 4-(para-substituted phenyl)-1,2,3-selenadiazole adducts of [VO(acac)2] were studied by density functional theory (DFT) calculations. The 4-(para-substituted phenyl)-1,2,3-selenadiazole molecules have been selected to be bound with vanadium atom in [VO(acac)2] through Se, N2 and N3. The resulting adducts have been investigated in two geometries (cis and trans) in order to show the effect of such structural change on the electronic properties of the studied adducts. The optimized geometries, (binding and reorganization) energies and the spatial distribution of the highest molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the adducts are presented and discussed.

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 

Electronic and geometric structure of AuxCuy clusters studied by density functional theory

2014 ◽  
Vol 25 (06) ◽  
pp. 1450011 ◽  
Author(s):  
Y. Kadioglu ◽  
O. Üzengi Aktürk ◽  
M. Tomak
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Density Functional ◽  
Local Density ◽  
Three Dimensional ◽  
Binding Energies ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

We have determined the stable structures of Au Cu n, Au 2 Cu n, Au 3 Cu n and Au x Cu 8-x clusters. It has been observed that Au Cu n, Au 2 Cu n and Au 3 Cu n systems have two-dimensional (2D) structures up to six atoms and they become three-dimensional (3D) afterwards. Au x Cu 8-x clusters favor 3D structures till the Au 7 Cu 1 cluster. We have found a lowest energy isomer of Au 6 Cu 2 from the literature. Bond lengths, binding energies, density of states (DOS), highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO-LUMO) gaps, ionization potential (IP) and electron affinity (EA) have been calculated for these structures using the first principles density functional theory (DFT) within the generalized gradient approximation (GGA) and the local density approximation (LDA). Generally, we have observed the overlap between s electrons of Cu and p electrons of Au near the Fermi level. Charge transfers are calculated by using the Löwdin analysis. It is observed that one Cu atom does not significantly modify the clusters which have more gold atoms. It is also seen that these clusters generally have nonmagnetic properties and results are consistent with the hybridization between s and d orbitals of Au in Au x Cu 8-x clusters.

scholarly journals Regulating the Optoelectronic Properties of Nickel Dithiolene by the Substituents: A Theoretical Study

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2192 ◽  
Author(s):  
Lili Sun ◽  
Siwei Shu ◽  
Yi Zhou ◽  
Sen Hou ◽  
Yan Liu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Density Functional ◽  
Near Infrared ◽  
Electron Transition ◽  
Optoelectronic Properties ◽  
Functional Theory ◽  
Organic Optoelectronic Devices ◽  
Lowest Unoccupied Molecular Orbital ◽  
Organic Optoelectronic

Dithiolene-based complexes show great potential to be applied as materials for organic optoelectronic devices. In this study, we theoretically designed a series of complexes based on nickel dithiolene and its substituted derivatives, the optoelectronic properties of which were comparatively studied by density functional theory (DFT)/time-dependent density functional theory (TD-DFT). The results show that the charge injection property of nickel dithiolene complexes can be significantly improved with introduction of electron-withdrawing groups. The charge transportation property of nickel dithiolene depends on the conjugation degree of the system. The energy gaps between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are determined by the substituents, which makes the maximum absorption wavelength red-shift from the visible to the near-infrared (NIR) region. The electron density difference graph shows that the electron transition from the ground state to the first excited state is assigned to π-π* transition mainly from HOMO to LUMO. The regularity of substituent effect revealed by us in this study will shed light on the application of nickel dithiolenes as potential optoelectronic materials.

scholarly journals Crystal structure, Hirshfeld surface analysis and density functional theory study of 6-methyl-2-[(5-methylisoxazol-3-yl)methyl]-1H-benzimidazole

2021 ◽  
Vol 77 (4) ◽  
pp. 396-401
Author(s):  
Ahlam Idrissi ◽  
Karim Chkirate ◽  
Nadeem Abad ◽  
Bahia Djerrari ◽  
Redouane Achour ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Surface Analysis ◽  
Density Functional ◽  
Energy Gap ◽  
Crystal Packing ◽  
Hirshfeld Surface ◽  
Hirshfeld Surface Analysis ◽  
Functional Theory ◽  
Lowest Unoccupied Molecular Orbital

In the title molecule, C13H13N3O, the isoxazole ring is inclined to the benzimidazole ring at a dihedral angle of 69.28 (14)°. In the crystal, N—H...N hydrogen bonds between neighboring benzimidazole rings form chains along the a-axis direction. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H...H (48.8%), H...C/C...H (20.9%) and H...N/N...H (19.3%) interactions. The optimized structure calculated using density functional theory at the B3LYP/6–311 G(d,p) level is compared with the experimentally determined structure in the solid state. The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap is 4.9266 eV.

scholarly journals ZnO Nanocrystal-Based Chloroform Detection: Density Functional Theory (DFT) Study

Coatings ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 769 ◽  
Author(s):  
H. Y. Ammar ◽  
H. M. Badran ◽  
Ahmad Umar ◽  
H. Fouad ◽  
Othman Y. Alothman
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Sensing Applications ◽  
Specific Geometry ◽  
Lowest Unoccupied Molecular Orbital ◽  
Zno Nanoclusters ◽  
Energy Frontier

We investigated the detection of chloroform (CHCl3) using ZnO nanoclusters via density functional theory calculations. The effects of various concentrations of CHCl3, as well as the deposition of O atoms, on the adsorption over ZnO nanoclusters were analyzed via geometric optimizations. The calculated difference between the highest occupied molecular orbital and the lowest unoccupied molecular orbital for ZnO was 4.02 eV. The most stable adsorption characteristics were investigated with respect to the adsorption energy, frontier orbitals, elemental positions, and charge transfer. The results revealed that ZnO nanoclusters with a specific geometry and composition are promising candidates for chloroform-sensing applications.

scholarly journals A computational study of the 1,3-dipolar cycloaddition reaction mechanism for nitrilimines

2005 ◽  
Vol 83 (9) ◽  
pp. 1615-1625 ◽  
Author(s):  
Robert C Mawhinney ◽  
Heidi M Muchall ◽  
Gilles H Peslherbe
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Density Functional ◽  
Computational Study ◽  
Cycloaddition Reaction ◽  
Bond Distance ◽  
Functional Theory ◽  
Barrier Heights ◽  
Transient Nature ◽  
Lowest Unoccupied Molecular Orbital

The [3+2] and [1+2] cycloaddition pathways between ethene and a series of 13 nitrilimines (R1CNNR2) have been examined by density functional theory [PBE0/6-311++G(2df,pd)] calculations. All reactions have low barriers ranging from 14.14 (R1 = CH3, R2 = H) to 1.01 (R1 = R2 = F) kcal mol–1, and large reaction exothermicities consistent with the transient nature of nitrilimines. The [3+2] and [1+2] transition-state structures are very similar, mainly differing in the relative orientation of their fragments and the newly forming C—C bond distance, and exhibit only minor deviations from the structures of the reactants. Both reaction pathways are concerted and asynchronous, but the [1+2] reaction has a greater degree of asynchronicity. Examination of the frontier molecular orbitals reveals that both the [3+2] and [1+2] barrier heights are related to two sets of orbital interactions, with the interaction between the lowest unoccupied molecular orbital π [Formula: see text] of nitrilimine and the highest occupied molecular orbital of ethene in common. The second interaction in both cases is carbene-like. A relationship between the weights of the 1,3-dipolar resonance contribution in the various nitrilimines and the corresponding [3+2] barrier heights was not found, but a good correlation could be found between the [1+2] barrier heights and both the 1,3-dipolar and carbene contributions. Inspection of the potential energy surface in the vicinity of the two transition states for the reaction between unsubstituted nitrilimine and ethene suggests that the observed [3+2] product is a result of an initial carbene-like approach of the two fragments followed by a ridge bifurcation that leads to the [3+2] product minimum. Key words: nitrilimines, 1,3-dipole, carbene, [3+2] cycloaddition, [1+2] cycloaddition, density functional theory (DFT).

scholarly journals DENSITY FUNCTIONAL THEORY INVESTIGATION FOR INSB NANOCRYSTAL DIAMANTANE DRUG CARRIER

2021 ◽  
Vol 03 (02) ◽  
pp. 18-27
Author(s):  
Methaq Talib MATROOD ◽  
Aqeel Adil HASAN
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Density Functional ◽  
Drug Carrier ◽  
National Level ◽  
Geometry Optimization ◽  
Basis Sets ◽  
Functional Theory ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

Nanomedicine remains the medicinalrequest of nanotechnology. Nanodrugvarietiesafter the medicinalrequests of nanoparticles, to nanoelectronic biosensors, thenuniform possible future applications of particle nanotechnology.Nanoparticle of medicationtransporters are optimized aimed atpreoccupation of medicationsfinishedbreathtreatment. Demonstrating and imitation of nanocrystal limits of the theophylline (C7H8N4O2)byindium – antimony (In7Sb7H20 (in diamantane constructionhave been performed by Gaussian 09 program. DFT hasremainedused for InSb nanoparticle, theophyllinemedication. Optimization and frequency on the ground national level,PBEPBE, 3-21G basis sets consumesremainedexamined. The custodiesaimed ataltogetherremainequivalenttoward zero custodies. The geometry optimization by means of both methods (PBE) for InSb diamantane nanoparticles and theophyllinedrug has been originate cutting-edgedecent agreement by experimental dataMolecular detour theory has been used to discovery highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies. Total energy, ionization potential and electron empathy have beenintendedaimed atInSbnanostructure bytheophyllinemedication.

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