In this research DFT/B3LYP method has been employed to investigate the geometrical structures, relative stabilities, and electronic properties of Cun (n=3–10) clusters for clarifying the effect of size on the properties. Through a careful analysis of the successive binding energies, second-order difference of energy and the highest occupied-lowest unoccupied molecular orbital energy gaps as a function of cluster size, an odd-even alternative phenomenon has been observed. The results show that the clusters with even number of copper atoms present relatively higher stabilities.

The Density Functional Theory (DFT) and the Natural Bond Orbital (NBO) calculations based method B3LYP/6-31G* were carried out to study the interaction of carbon nanotube (8, 0) with nitrobenzene in two situations perpendicular and parallel. Formation energies of compounds, charges, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) and the HOMO-LUMO band gap were calculated. The parallel direction is more stable than the perpendicular direction. The lower HOMO-LUMO gaps confirm this stability.

Electron-phonon coupling parameters are calculated for La2-xBaxCuO4 cuprate superconductor in a wide range of dopings, from undoped to overdoped compounds. In this study we aim to study the quality of such calculations based on DFT method so, the results of scoupling is in the same order of previous calculations but, the value obtained for the Hubbard U parameter shows that, such methods are poor in the estimation of electronic correlations to decide about the role of phonons in these compounds based on their results. Moreover, existence of several structural phase transitions with temperature and doping, lead to larger error in these calculations. Based on the calculated phonon dispersions, structural phase transitions can be resulted which shows the ability of DFT in the study of structural properties and the weakness of the strongly correlations in this properties.

The Density Functional Theory (DFT) and the Natural Bond Orbital (NBO) calculations based method B3LYP/6-31G were carried out to study the interaction of Dopamine with carbon nanotube. The nanotube used in this study, includes 60 C atoms (6, 6) type. Relative and formation energies of compounds, Muliken charges, occupancy, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), the HOMO-LUMO band gap and the electronic chemical potential (m) were calculated. The NBO analysis showed there is a hyperconjugative interaction between Oxygen and Nitrogen lone-pair electrons of dopamine and s* or p* orbitals of carbon atom of nanotube. Results indicated that the composite between nanotubes and the Ncentered dopamine is more stable than O1-centered dopamine and both of them are stable than the single agent.

In this paper, the synthesis of various enaminones from the reaction of 3-aminocoumarin and ethyl-2, 4-dioxo-4-arylbutanoate in the presence of p-toluene sulfonic acid is reported. The reaction was examined under different solvents and catalytic systems, which clearly proved the importance of acidic catalyst in this organic transformation. This work was also accompanied by density functional theory (DFT) studies to justify the formation of final products.

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.

Electrons of orbitals near to nuclei of heavy atoms acquire speeds comparable to the speed of light in vacuum. Therefore, to study the properties of crystals containing heavy atoms, it is necessary to take into account the relativistic effects. In this work, using the first-principles DFT+U method, we have calculated the electronic structure and geometric properties of uranium dioxide UO2 within full-relativistic, scalar-relativistic, and non-relativistic formulations, and compared the results. It is shown that: (i) the non-relativistic scheme gives results very far form experimental values for both lattice constant and bang gap; (ii) in full-relativistic case which the spin-orbit effects are included, the Kohn-Sham band-gap is increased by 6.2% and the lattice constant decreases by 0.05% compared to scalar-relativistic one. Therefore, in the study of geometric properties of UO2, using the scalar-relativistic regime is quite accurate and one does not need to perform much more expensive full-relativistic calculations whenever one does not study the electronic excitation properties.

The molecular structure of Cyclophosphamide (‘N, N-bis (2-chloroethyl) -1, 3, 2-oxazaphosphinan-2-amine 2-oxide’ is the anti cancer drug and used to treat cancer and immune diseases) and SWCNTs were calculated by the B3LYP density functional model with 6-311G* basis set with Gaussian 09 program. The nanotube used in this study, includes 120 C atoms (5, 5) type. The NBO analysis showed there is a hyperconjugative interaction between Oxygen lone-pair electrons of Cyclophosphamide and s* οr  p* orbitals of carbon atom of nanotube. Also chemical shift isotropy (s), chemical shift anisotropy (D s) ), asymmetry parameter( h) of this compounds have been reported.

An azobenzene bridge was introduced into the lower (or smaller) rim of p-tert-butylcalix [8] arene to form 1, 5-singly bridged calix [8] arene derivatives, respectively. Bridged calix [8] arene of conformationally rigid were isolated. The stability of the two structures of bridged calix [8] arenes have been compared.The study of organic structure to form nanoporous structures is a well known in chemistry phenomena to finding crystal structure of calix [8] arene as supramolecular chemistry. The effect of hydrogen bonding on calix [8] arene was reported at Density Functional Theory by Gaussian 98 of program package. The self assembled nanotubes in solid state through network hydrogen bonds between the chains of this structure were investigated.