The effect of the adsorbed thiophene (T) on the surface of (8,0) zigzag single walled Boron Nitride Nanotubes (BNNTs) was studied using density functional theory calculations in the gas phase. Geometry optimizations were also carried out at the B3LYP/6-31G (d) level of theory. The Gaussian 09 suites of programs were used. The geometric optimization of (8, 0) BNNT-T was performed using the minimum energy criterion in six different configurations of the adsorbed thiophene on the Nanotube. Our computer simulations have found that the preferred adsorption site of the molecule is at the end of the Nanotube for the T component and all cases have physical interactions. The results showed an increase in polarity due to the proper distribution of electrons. It was also found that the reduction in global hardness, energy gap and electronic chemical potential due to thiophene adsorption leads to an increase in the stability of the (8,0) zigzag BNNT-T complex. In this study, natural bond analysis, global softness, ionization potential and electrophilicity index for Nanotubes were calculated.

In this research, the interaction of Boron Nitride (6,6) Nanotubes with a length of 8 nm with vitamin B6 (pyridoxal phosphate) was theoretically investigated and the effects of electron destabilization, dipole-dipole interactions and steric repulsions on the structural and electronic properties and The reactivity of vitamin B6 (pyridoxal phosphate) in the presence of single-wall Boron Nitride (6.6) Nanotubes with a length of 8 angstroms was studied using density functional theory quantum mechanical calculations at the B3LYP computational theoretical level and G* 31-6 basis series. . In order to determine the electrical conductivity and chemical behavior of Boron Nitride Nanotubes in reaction with vitamin B6, electron energies, dipole moments, energy gap of homo-lomo molecular orbitals, chemical hardness (η), electron chemical potential (μ) And Mulliken's electronegativity (χ) and adsorption energy (EAd) were investigated in the gas and solvent phases. The results showed that the adsorption energy in the gas and solvent phases is -12.962 and -7.895 kcal/mol, respectively, which shows that the adsorption reaction is feasible in both phases in terms of energy. In the gaseous phase, the energy gap in the encapsulated vitamin B6-Boron Nitride Nanotube mixture (3.517 Eg= electron volts) has decreased compared to the energy gap in the vitamin B6 molecule alone (4.561 Eg= electron volts). In the vitamin B6-Boron Nitride Nanotube encapsulated mixture, with the reduction of the Eg energy gap, the hardness parameter has decreased, the softness parameter has also decreased, and the electronegativity and electrophilicity values ​​have increased.

Based on the semi-empirical methods to obtain the vibration model of molecule, the zigzag single-walled Boron Nitride Nanotube (BNNTs) with (8, 0) structure were investigated.Geometry optimizations and vibrational frequencies of BNNTs were carried out at AM1, CNDO, MNDO, M1NDO3 and MC using hyperchem 6 suites of program. The combination and their normalization coefficients of (8, 0) Nanotube in C6V point group was calculated and the effect of dielectric constants on the mechanism of these vibrations in Nanotubes was studied. This study show that in the high dielectric, the frequency of vibration has alternative behavior, but by the decreasing of the dielectric, this behavior change to stable situation of geometry.

The melting of zigzag, armchair and chiral single walled Boron Nitride Nanotubes (SWBNs) investigated using molecular dynamics (MD) simulation based on Tersoff-like many body potential. The MD simulation has been employed in the constant pressure, constant temperature (NPT) ensemble. The temperature and pressure of the system were controlled by Nose-Hoover thermostat and Berendsen barostat, respectively. We have computed the variation of the melting temperature with the radius of BN Nanotube. The results show that the melting temperature of Nanotubes increase with increasing in the size of radii, but this dependence is not the same for the various chiral angle of Nanotubes. The relation of the melting point with radius for three types of Nanotubes i. e. zigzag, armchair and chiral obtained. Moreover, our results show that the melting temperature of Nanotubes approach a constant value at larger radii.

In this paper, free vibration analysis of a polymer-based nano-composite beam reinforced by Boron-Nitride Nanotubes and subjected on elastic foundation, is studied. Smooth and defect-free Nanotubes with uniform and directly- orientated in matrix are intended. Also, Nanotubes’ distribution in the thickness direction of beam is regarded as a uniform distribution of the three different targeted ones. The properties of nano-beam are obtained by using a micromechanical model. The governing equations based on Timoshenko beam theory are derived by using the Hamilton principle. The equations are solved by the extended differential Quadrature and the natural frequencies are obtained. The effect of various parameters such as volume fraction of Nanotubes, carbon-Nanotube (CNT) distribution in the thickness direction of the beam, elastic media, boundary conditions and the aspect ratio is investigated on the natural frequency. The results show that a change on these parameters has a significant impact on the natural frequency.