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Hewa Y. Abdullah

Other affiliations: University of Milan, University of Mosul, Salahaddin University  ...read more
Bio: Hewa Y. Abdullah is an academic researcher from International University, Cambodia. The author has contributed to research in topics: Density functional theory & Natural bond orbital. The author has an hindex of 12, co-authored 78 publications receiving 477 citations. Previous affiliations of Hewa Y. Abdullah include University of Milan & University of Mosul.


Papers
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Journal ArticleDOI
TL;DR: It was revealed that the sensitivity of the adsorption will be increased when the gas molecule interacts with decorated nanosheets and decrease the HOMO-LUMO band gap; therefore, the change of electronic properties can be used to design suitable nanosensors to detect CFM gas.
Abstract: In the present investigation, the feasibility of detecting the chlorofluoromethane (CFM) gas molecule onto the outer surface of pristine single layer boron nitride nanosheet (BNNS), as well as its aluminum (Al)- and gallium (Ga)-doped structures, was carefully evaluated. For achieving this goal, a density functional theory level of study using the Perdew, Burke, and Ernzerhof exchange-correlation (PBEPBE) functional together with a 6-311G(d) basis set has been used. Subsequently, the B3LYP, CAM-B3LYP, wB97XD, and M062X functionals with a 6-311G(d) basis set were also employed to consider the single-point energies. Natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) were implemented by using the B3LYP-D3/6-311G(d) method, and the results were compatible with the electronic properties. In this regard, the total density of states (TDOSs), the Wiberg bond index (WBI), natural charge, natural electron configuration, donor-acceptor natural bond orbital interactions, and the second-order perturbation energies are performed to explore the nature of the intermolecular interactions. All of the energy calculations and population analyses denote that by adsorbing of the gas molecule onto the surface of the considered nanostructures, the intermolecular interactions are of the type of strong chemical adsorption. Among the doped nanosheets, Ga-doped nanosheet has very high adsorption energy compared with other elements (i.e., Ga-doped > Al-doped > pristine). Generally, it was revealed that the sensitivity of the adsorption will be increased when the gas molecule interacts with decorated nanosheets and decrease the HOMO-LUMO band gap; therefore, the change of electronic properties can be used to design suitable nanosensors to detect CFM gas. Graphical abstract.

41 citations

Journal ArticleDOI
TL;DR: In this article, the effect of external magnetic and AB flux fields on the energy spectra of the system is examined in detail, and it is found that the AB field performs better than the magnetic field in its ability to remove degeneracy.
Abstract: In this research work, the Hellmann potential is studied in the presence of external magnetic and AB flux fields within the framework of Schrodinger equation using the Nikiforov–Uvarov functional analysis method. The energy equation and wave function of the system are obtained in closed form. The effect of the fields on the energy spectra of the system is examined in detail. It is found that the AB field performs better than the magnetic field in its ability to remove degeneracy. Furthermore, the magnetization and magnetic susceptibility of the system were discussed at zero and finite temperatures. We evaluate the partition function and use it to evaluate other thermodynamic properties of the system such as magnetic susceptibility, $$ \chi_{\text{m}} \left( {\vec{B},\varPhi_{\text{AB}} ,\beta } \right) $$ , Helmholtz free energy $$ F\left( {\vec{B},\varPhi_{\text{AB}} ,\beta } \right) $$ , entropy $$ S\left( {\vec{B},\varPhi_{\text{AB}} ,\beta } \right) $$ , internal energy $$ U\left( {\vec{B},\varPhi_{\text{AB}} ,\beta } \right) $$ and specific heat $$ C_{v} \left( {\vec{B},\varPhi_{\text{AB}} ,\beta } \right) $$ . A comparative analysis of the magnetic susceptibility of the system at zero and finite temperatures shows a similarity in the behavior of the system. A straightforward extension of our results to three dimensions shows that the present result is consistent with what is obtained in the literature.

36 citations

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TL;DR: In this paper, density functional techniques (DFT) were put into practice to study the nature of the intermolecular interactions between Vinyl chloride (VCM) gas molecule with single-walled pristine, Al and Ga-doped boron nitride nanotubes (BNNT, BNAlNT, and BNGaNT, respectively).

31 citations

Journal ArticleDOI
TL;DR: In this paper , the use of boron nitride nanosheets (BNNS) and its aluminum and gallium doped derivatives as sensors for dichlorosilane (C 3 H 7 NO 3 ) gas molecule was studied by employing the B3LYP-D3 model with the 6-311G(d) basis set as well as the PBE0, ωB97XD, and M06-2X functionals.

31 citations

Journal ArticleDOI
TL;DR: In this paper, the free vibration of symmetric and antisymmetric cross-ply composite laminated truncated conical shells using the spline function technique is studied, including first-order shear deformation theory.
Abstract: Free vibration of symmetric and antisymmetric cross-ply composite laminated truncated conical shells using the spline function technique is studied. The equilibrium equations for a truncated conical shells are formulated including first-order shear deformation theory. The equations of motion are derived in terms of displacement functions and rotational functions using stress–strain and strain–displacement relationships. The coupled differential equations are solved using Bickley-type splines to obtain the generalized eigenvalue problem by combining suitable boundary conditions. The convergence and comparative results are presented. Both symmetric and anti-symmetric cross-ply shells are considered using various types of material properties. Parametric studies are made to investigate the effect of transverse shear deformation on the frequency parameter with respect to the thickness ratio, length ratio, cone angle, and circumferential mode number using different numbers of layers under various types of boundary conditions.

30 citations


Cited by
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01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

1,652 citations

01 Apr 2001
TL;DR: In this paper, the reduced electric quadrupole transition probability, B(E2)↑, from the ground state to the first-excited 2+ state of even-even nuclides are given in Table I.
Abstract: Adopted values for the reduced electric quadrupole transition probability, B(E2)↑, from the ground state to the first-excited 2+ state of even–even nuclides are given in Table I. Values of τ, the mean life of the 2+ state; E, the energy; and β, the quadrupole deformation parameter, are also listed there. The ratio of β to the value expected from the single-particle model is presented. The intrinsic quadrupole moment, Q0, is deduced from the B(E2)↑ value. The product E×B(E2)↑ is expressed as a percentage of the energy-weighted total and isoscalar E2 sum-rule strengths. Table II presents the data on which Table I is based, namely the experimental results for B(E2)↑ values with quoted uncertainties. Information is also given on the quantity measured and the method used. The literature has been covered to November 2000. The adopted B(E2)↑ values are compared in Table III with the values given by systematics and by various theoretical models. Predictions of unmeasured B(E2)↑ values are also given in Table III.

955 citations

Journal ArticleDOI
02 Apr 1982-Science

556 citations

Journal ArticleDOI
TL;DR: In this paper, an asymptotic interation method for solving second-order homogeneous linear differential equations of the form y'' = lambda(x) y' + s(x), y is introduced.
Abstract: An asymptotic interation method for solving second-order homogeneous linear differential equations of the form y'' = lambda(x) y' + s(x) y is introduced, where lambda(x) eq 0 and s(x) are C-infinity functions. Applications to Schroedinger type problems, including some with highly singular potentials, are presented.

415 citations