الفهرس 
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Abstract
Summary
This thesis presents a theoretical study of the effects of distortions on hydrogen storage on the single-wall boron nitride nanotubes (SWBNNTs) decorated with nickel to obtain the best storage capacity of hydrogen on the BNNTs by applying ab initio calculations using Gaussian system, Gauss View, and Gauss Sum. Density functional calculations are used in the theoretical study of hydrogen storage on Ni-doped zigzag SWBNNTs (8,0)
Chapter 1, includes a brief introduction for the different methods used to store hydrogen, the use of single-wall boron nitride nanotubes (SWBNNTs) to store hydrogen.
In chapter 2, a theoretical review for the basic molecular electronic structure methods (Hartree - Fock and density functional theory) is given.
In chapter 3, a literature survey in the field of study is given.
In chapter 4,
The influence of mechanical bending to tuning the hydrogen storage of Ni-functionalized of zigzag type of boron nitride nanotubes (BNNTs) has been investigated using density functional theory (DFT) with reference to the ultimate targets of the US Department of Energy (DOE). Single Ni atoms prefer to bind strongly at the axial bridge site of BN nanotube, and each Ni atom bound on BNNT may adsorb up to five, H2 molecules, with average adsorption energies per hydrogen molecule of (- 1.622,-0.527 eV) for the undeformed 〖(B〗_40 N_40-φ = 0º )&(-1.62 ,0 -0.308 eV) for the deformed 〖(B〗_40 N_40-φ =15º )& (-1.589,-0.310 eV) for the deformed 〖(B〗_40 N_40-φ =30º ) and (-1.368 - -0.323 eV) for the deformed 〖(B〗_40 N_40-φ =45º ) respectively. with the H-H bonds between H2 molecules significantly elongated. The curvature attributed to the bending angle has effect on average adsorption energies per H2 molecule. With no metal clustering, the system gravimetric capacities are expected to be as large as 5.691 wt % for 〖(5H_2-Ni-B〗_40 N_40-φ =0º,15º,30º,45º ). While the desorption activation barriers of the complexes 〖(nH_2-Ni-B〗_40 N_40-φ =0º ) (n = 1-4) are outside the (DOE) domain (-0.2 to -0.6 eV), the complexes 〖(5H_2-Ni-B〗_40 N_40-φ =0º ) is inside this domain. For 〖(nH_2-Ni-B〗_40 N_40-φ =15º,30º,45º )with (n = 1-2) are outside the (DOE) domain, the complexes 〖(nH_2-Ni-B〗_40 N_40-φ =15º,30º,45º ) with (n = 3-5) are inside this domain. The hydrogen storage of the irreversible 4H2+ Ni- B40N40-φ = 0 º, 2H2+ Ni- B40N40-φ = 15º,30º,45º and reversible 5H2+ Ni- B40N40-φ = 0º, 3H2+ Ni- B40N40-φ = 15º,30º,45º interactions are characterized in terms of density of states, pairwise and non-pairwise additivity, infrared, Raman, electrophilicity and molecular electrostatic potentials. Our calculations expect that 5H2- Ni- B40N40- φ = 0 º, 15º,30º,45º complexes are promising hydrogen storage candidates.
In chapter 5,
The effect of axial deformation on tuning the hydrogen storage of nickel functionalized (8, 0) zigzag boron nitride nanotube is investigated by using density functional theory calculations. The assessment has been carried out based on the adsorption of molecular hydrogen with the binding energy lying in the desirable energy window, charge transfer, the density of states, pairwise and nonpairwise additivty, frontier orbital band gaps, isosurface plots, polarizabilities and hyperpolarizabilities, simulated Infrared (IR) and Raman (R). The numerous changes in adsorption energy of H2 upon relaxation or compression of only (1%) strain points to the sensitivity of H2 binding to axial deformation effects. The calculated pairwise and non-pairwise additive components show that the role of the BNNT is not restricted to support the metal. Spectral analysis additionally as polarizability and hyperpolarizability calculations characterize the relaxed structure (Z = 1.01), that H2 adsorption energy (−0.552 eV) is within the suggested energy vary for hydrogen storage, to be energetically additional desirable than the compressed structure (Z = 0.99). The results provide some way to manage and characterize the hydrogenation process of metal functionalized BNNTs by strain loading.