Adsorption Properties of O2onCr5Nanostructures: A DFT Study

The density functional theory (DFT) has been used to simultaneously investigate physic/chemi-sorption properties of oxygen on the (5, 5) boron nitride nanotube (BNNT). Geometry optimizations were carried out at B3LYP/6-31G*level of theory using gaussian 98 suites of program. physisorption of O2outside the BNNT with a vertical orientation to the tube axis above a boron atom is the most stable state of physisorption and its binding energy is -0.775 kcal/mol. In the chemisorption of O2molecule, the most stable state is above two adjacent B and N atoms of a hexagon with a B-N bond length of 2.503 Å and the binding energy of adsorbed oxygen atoms -14.389 kcal/mol. Based on these results, We also provide the effects of O2adsorption on the electronic properties of BNNTs.

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On the Use of DFT+U to Describe the Electronic Structure of TiO2 Nanoparticles: (TiO2)35 as a Case Study

10.26434/chemrxiv.12213536.v1 ◽

2020 ◽

Author(s):

Angel Morales ◽

Stephen Rhatigan ◽

Michael Nolan ◽

Frances Illas

Keyword(s):

Density Functional ◽

Energy Gap ◽

Plane Waves ◽

Basis Set ◽

Basis Sets ◽

Functional Theory ◽

The Density Functional Theory ◽

Structural And Electronic Properties ◽

Rotationally Invariant

One of the main drawbacks in the density functional theory (DFT) formalism is the underestimation of the energy gaps in semiconducting materials. The combination of DFT with an explicit treatment of electronic correlation with a Hubbard-like model, known as DFT+U method, has been extensively applied to open up the energy gap in materials. Here, we introduce a systematic study where the selection of U parameter is analyzed considering two different basis sets: plane-waves (PWs) and numerical atomic orbitals (NAOs), together with different implementations for including U, to investigate the structural and electronic properties of a well-defined bipyramidal (TiO2)35 nanoparticle (NP). This study reveals, as expected, that a certain U value can reproduce the experimental value for the energy gap. However, there is a high dependence on the choice of basis set and, and on the +U parameter employed. The present study shows that the linear combination of the NAO basis functions, as implemented in FHI-aims, requires a lower U value than the simplified rotationally invariant approaches as implemented in VASP. Therefore, the transferability of U values between codes is unfeasible and not recommended, demanding initial benchmark studies for the property of interest as a reference to determine the appropriate value of U.

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Theoretically studying the optoelectronic properties of oligomers based on 2.7-divinyl-cabazole

Eclética Química Journal ◽

10.26850/1678-4618eqj.v47.1.2022.p40-54 ◽

2022 ◽

Vol 47 (1) ◽

pp. 40-54

Author(s):

Mohamed Jabha ◽

Abdellah El Alaoui ◽

Abdellah Jarid ◽

El Houssine Mabrouk

Keyword(s):

Density Functional ◽

Energy Surface ◽

Energy Gap ◽

Dft Method ◽

Photovoltaic Cell ◽

Organic Photovoltaic ◽

Functional Theory ◽

Total Potential ◽

The Density Functional Theory ◽

Homo Lumo

This work consists of theoretically studying the electronic and optical properties of 9-(4-octyloxyphenyl)-2.7-divinyl-carbazole (PCrV) oligomers. This study has been undertaken using the density functional theory (DFT) method at the B3LYP/6-31G (d,p) level and BP86/6-31G (d,p) level of theory. To evaluate the PCrV-basis systems properties, the structural optimization without geometrical restrictions was performed on the total potential energy surface (TPES). In order to ensure good absorption of radiation, the interest was in increasing the efficiency of the organic photovoltaic cell. For this effect, the (HOMO-LUMO) gap energy of such compounds was reduced in terms of geometric and electronic structure. The BP86 functional gives good results at the energy gap level, while other parameters using the B3LYP functional give the best results.

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Vibrational Spectroscopic and Computational Analysis of 5-chloro-2-hydroxy Acetophenone

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.d1043.1284s419 ◽

2020 ◽

Vol 8 (4S4) ◽

pp. 254-259

Keyword(s):

Density Functional ◽

Computational Analysis ◽

Energy Gap ◽

Molecular System ◽

Basis Sets ◽

Geometrical Parameters ◽

Lumo Energy ◽

Functional Theory ◽

Infrared Intensities ◽

Homo Lumo

Fourier Transfer infrared and Raman spectra in the range of 4000-400 cm-1 and 3500-50 cm-1 were recorded to study the vibrational spectra of 5-chloro-2-hydroxyacetophenone (CHAP). Using density functional theory (DFT/B3LYP) with 6-31+G(d,p) and 6-311++G(d,p) basis sets the various geometrical parameters such as Raman activities, infrared intensities and optimum frequencies were calculated. The HOMO-LUMO energy gap has been computed which confirms the charge transfer of the molecular system. Mulliken’s atomic charges associated with each atom and thermodynamic parameters have also been reported with the same level of DFT.

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Crystal structure, Hirshfeld surface analysis and DFT studies of (E)-4-methyl-2-{[(4-methylphenyl)imino]methyl}phenol

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989020007847 ◽

2020 ◽

Vol 76 (7) ◽

pp. 1075-1079

Author(s):

Nermin Kahveci Yagci ◽

Md. Serajul Haque Faizi ◽

Alev Sema Aydin ◽

Necmi Dege ◽

Onur Erman Dogan ◽

...

Keyword(s):

Crystal Structure ◽

Surface Analysis ◽

Density Functional ◽

Energy Gap ◽

Hirshfeld Surface ◽

Hirshfeld Surface Analysis ◽

Functional Theory ◽

Compound C ◽

The Density Functional Theory ◽

Homo Lumo

In the title compound, C15H15NO, the configuration of the C=N bond of the Schiff base is E, and an intramolecular O—H...N hydrogen bond is observed, forming an intramolecular S(6) ring motif. The phenol ring is inclined by 45.73 (2)° from the plane of the aniline ring. In the crystal, molecules are linked along the b axis by O—H...N and C—H...O hydrogen bonds, forming polymeric chains. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the packing arrangement are from H...H (56.9%) and H...C/C...H (31.2%) interactions. The density functional theory (DFT) optimized structure at the B3LYP/ 6–311 G(d,p) level is compared with the experimentally determined molecular structure, and the HOMO–LUMO energy gap is provided. The crystal studied was refined as an inversion twin.

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On the Use of DFT+U to Describe the Electronic Structure of TiO2 Nanoparticles: (TiO2)35 as a Case Study

10.26434/chemrxiv.12213536 ◽

2020 ◽

Author(s):

Angel Morales ◽

Stephen Rhatigan ◽

Michael Nolan ◽

Frances Illas

Keyword(s):

Density Functional ◽

Energy Gap ◽

Plane Waves ◽

Basis Set ◽

Basis Sets ◽

Functional Theory ◽

The Density Functional Theory ◽

Structural And Electronic Properties ◽

Rotationally Invariant

One of the main drawbacks in the density functional theory (DFT) formalism is the underestimation of the energy gaps in semiconducting materials. The combination of DFT with an explicit treatment of electronic correlation with a Hubbard-like model, known as DFT+U method, has been extensively applied to open up the energy gap in materials. Here, we introduce a systematic study where the selection of U parameter is analyzed considering two different basis sets: plane-waves (PWs) and numerical atomic orbitals (NAOs), together with different implementations for including U, to investigate the structural and electronic properties of a well-defined bipyramidal (TiO2)35 nanoparticle (NP). This study reveals, as expected, that a certain U value can reproduce the experimental value for the energy gap. However, there is a high dependence on the choice of basis set and, and on the +U parameter employed. The present study shows that the linear combination of the NAO basis functions, as implemented in FHI-aims, requires a lower U value than the simplified rotationally invariant approaches as implemented in VASP. Therefore, the transferability of U values between codes is unfeasible and not recommended, demanding initial benchmark studies for the property of interest as a reference to determine the appropriate value of U.

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Theoretical investigation on vibrational spectroscopic and nonlinear optical activity of 1-(4-chloro phenyl)-3-(4-dimethylamino phenyl) prop-2-en-1-one

Canadian Journal of Physics ◽

10.1139/cjp-2016-0684 ◽

2017 ◽

Vol 95 (4) ◽

pp. 353-360

Author(s):

Xiao-Hong Li ◽

Hong-Ling Cui ◽

Rui-Zhou Zhang

Keyword(s):

Density Functional ◽

Nonlinear Optical ◽

Energy Gap ◽

Density Functional Theory Method ◽

Nbo Analysis ◽

Frontier Molecular Orbital ◽

Functional Theory ◽

The Density Functional Theory ◽

Electron Donation ◽

Homo Lumo

The density functional theory method was used to calculate the vibrational spectrum, geometrical structure of 1-(4-chloro phenyl)-3-(4-dimethylamino phenyl) prop-2-en-1-one in the ground state. The analysis of natural bond orbital (NBO) was also performed. The infrared spectrum was obtained and interpreted by means of potential energies distributions. NBO analysis shows that electron donation from LP(1)N atom to the anti-bonding acceptor σ*(C6–C12) of the phenyl ring results in the stabilization of 43.9 kJ/mol. The predicted NLO properties show that the βtot of the title compound is larger than that of urea and is a good candidate as a nonlinear optical material. In addition, the frontier molecular orbital is also investigated. The high βtot value and the low HOMO–LUMO energy gap assert the suitability of the grown crystal for NLO applications.

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Crystal structure, Hirshfeld surface analysis and DFT studies of 4-methyl-2-({[4-(trifluoromethyl)phenyl]imino}methyl)phenol

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989020009615 ◽

2020 ◽

Vol 76 (8) ◽

pp. 1325-1330

Author(s):

Md. Serajul Haque Faizi ◽

Emine Berrin Cinar ◽

Onur Erman Dogan ◽

Alev Sema Aydin ◽

Erbil Agar ◽

...

Keyword(s):

Surface Analysis ◽

Density Functional ◽

Energy Gap ◽

Crystal Packing ◽

Hirshfeld Surface ◽

Hirshfeld Surface Analysis ◽

Functional Theory ◽

Compound C ◽

The Density Functional Theory ◽

Homo Lumo

The title compound, C15H12F3NO, crystallizes with one molecule in the asymmetric unit. The configuration of the C=N bond is E and there is an intramolecular O—H...N hydrogen bond present, forming an S(6) ring motif. The dihedral angle between the mean planes of the phenol and the 4-trifluoromethylphenyl rings is 44.77 (3)°. In the crystal, molecules are linked by C—H...O interactions, forming polymeric chains extending along the a-axis direction. The Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from C...H/H...C (29.2%), H...H (28.6%), F...H/H...F (25.6%), O...H/H...O (5.7%) and F...F (4.6%) interactions. The density functional theory (DFT) optimized structure at the B3LYP/6-311 G(d,p) level is compared with the experimentally determined molecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap. The crystal studied was refined as an inversion twin.

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STRUCTURES, ABSORPTION SPECTRA, AND ELECTRONIC PROPERTIES OF POLYFLUORENE AND ITS DERIVATIVES: A THEORETICAL STUDY

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633606002520 ◽

2006 ◽

Vol 05 (03) ◽

pp. 595-608 ◽

Cited By ~ 13

Author(s):

KRIENGSAK SRIWICHITKAMOL ◽

SONGWUT SURAMITR ◽

POTJAMAN POOLMEE ◽

SUPA HANNONGBUA

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Energy Gap ◽

Level Energy ◽

Excitation Energies ◽

Lumo Energy ◽

Functional Theory ◽

Local Energy Minimum ◽

Pi Systems ◽

Homo Lumo

The structural and energetic properties of polyfluorene and its derivatives were investigated, using quantum chemical calculations. Conformational analysis of bifluorene was performed by using ab initio (HF/6-31G* and MP2/6-31G*) and density functional theory (B3LYP/6-31G*) calculations. The results showed that the local energy minimum of bifluorene lies between the coplanar and perpendicular conformation, and the B3LYP/6-31G* calculations led to the overestimation of the stability of the planar pi systems. The HOMO-LUMO energy differences of fluorene oligomers and its derivatives — 9,9-dihexylfluorene (DHPF), 9,9-dioctylfluorene (PFO), and bis(2-ethylhexyl)fluorene (BEHPF) — were calculated at the B3LYP/6-31G* level. Energy gaps and effective conjugation lengths of the corresponding polymers were obtained by extrapolating HOMO-LUMO energy differences and the lowest excitation energies to infinite chain length. The lowest excitation energies and the maximum absorption wavelength of polyfluorene were also performed, employing the time-dependent density functional theory (TDDFT) and ZINDO methods. The extrapolations, based on TDDFT and ZINDO calculations, agree well with experimental results. These theoretical methods can be useful for the design of new polymeric structures with a reducing energy gap.

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CH2O Adsorption on M (M = Li, Mg and Al) Atom Deposited ZnO Nano-Cage: DFT Study

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.786.384 ◽

2018 ◽

Vol 786 ◽

pp. 384-392 ◽

Cited By ~ 2

Author(s):

Hussein Y. Ammar

Keyword(s):

Density Functional Theory ◽

Bond Length ◽

Density Functional ◽

Functional Theory ◽

The Density Functional Theory ◽

Structural And Electronic Properties ◽

Formaldehyde Molecule ◽

Electronic Configurations ◽

Adsorption Energies ◽

Homo Lumo

The structural and electronic properties of Li, Mg and Al deposited ZnO nanocages and their effects on the adsorption of formaldehyde molecule have been investigated using the density functional theory (DFT) computations. To understand the behavior of the adsorbed CH2O molecule on the ZnO nanocage, results of DFT calculations of the M-deposited nanocages (M=Li, Mg and Al), as well as complex systems consisting of the adsorbed CH2O molecule on M-deposited ZnO nanocage were reported. The results presented include adsorption energies, bond lengths, electronic configurations, density of states and molecular orbitals. It was found that, the most energetically stable adsorption configurations of CH2O molecule on the bare ZnO leads to 12% dilation in C=O bond length of CH2O and 14% decrease in HOMO-LUMO gap of ZnO cluster. The most energetically stable adsorption configurations of CH2O molecule on Li, Mg and Al-deposited ZnO lead to 4%, 4% and 11% dilation in C=O bond length of CH2O and-0.66, -45 and , +66% change in HOMO-LUMO gap of ZnO nanocages, respectively. The interaction between CH2O with bare ZnO and M-deposited ZnO nanocages is attributed to charge transfer mechanism. These results may be meaningful for CH2O degradation and detection.

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