The hydrogen storage outside and inside carbon nanotube (CNT) has investigated at different positions using density functional theory (DFT) and applying 6-31g basis set.In addition, the effect of vacancy defects on hydrogen storage has been studied including mono-vacancy, di-vacancy and isolated monovacancy defects.The adsorption energy, HOMO (highest occupied molecular Orbital), LUMO (lowest unoccupied molecular orbital), energy gap, dipole moment and Mullikan Analysis are discussed.The results show that hydrogen molecule cannot be stored inside the CNT.However, the hydrogen molecule prefers to be stored outside the nanotubes.The most candidate CNT for hydrogen storge is found to be mono-vacancy defected CNT with hydrogen adsorption energy -3.8 eV.

The electronic, magnetic, and optical characteristics of hexaazabipyH2 molecule (HA) and the 3d transition metal complexes for hexaazabipyH2 (TMHA) are investigated utilizing DFT and TD-DFT calculations. The sta-bility of the investigated complexes is confirmed by the binding energy, molecular dynamic, and vibrational frequencies. The calculated HOMO-LUMO gap values show that the HA and TMHA are semiconductors. The magnetic moment (& mu;) for the investigated complexes is estimated, and the greatest & mu; value (3.76 & mu;B) is recorded for the CrHA complex. The existence of the TM atom influences the UV-Vis spectrum of HA, where a redshift has occurred for the TMHA complexes except the ZnHA. The MnHA complex has a high light harvesting efficiency value of 0.403. The HA and TMHA complexes have refractive indices in the range of 2.311 to 3.323. Our results show that the HA as well TMHA complexes might be promising materials for solar cells and optoelectronics applications.

This work introduces DFT-D3 calculations to investigate the adsorption properties of The CH2O molecule on the Be12O12 nano-cage. The DFT-D3 calculations are performed using B3LYP/6-311 g(d,p). PDOS, NBO atomic charges, charge density difference, and QTAIM analyses are achieved. The impact of solvent, external static electric field (EF), and concentration of CH2O are examined. The CH2O molecule is chemically adsorbed on the Be12O12 nano-cage. The adsorption energy (Eads) and the HOMO-LUMO gap (Eg), consequently, the sensitivity, response time, and recovery time are controlled by the type of solvent, the electric field, and the concentration of CH2O. The Eads in the vacuum is -0.947 eV while in presence of negative EF enhanced it by 15.61 %. The Eg of Be12O12 is 7.870 eV whereas it reduced due to the adsorption of CH2O to 5.029 eV, then to 4.439 eV in the presence of the negative EF and to 3.688 eV at a high concentration of CH2O. Therefore, the results suggest that the Be12O12 nano-cage is a promising sensor for formaldehyde gas.

Theoretical calculations based on the Density Functional Theory (DFT) have been performed to investigate the interaction of H2S as well SO2 gaseous molecules at the surfaces of Be12O12 and Mg12O12 nano-cages. The results show that a Mg12O12 nano-cage is a better sorbent than a Be12O12 nano-cage for the considered gases. Moreover, the ability of SO2 gas to be adsorbed is higher than that of H2S gas. The HOMO–LUMO gap (Eg) of Be12O12 nano-cage is more sensitive to SO2 than H2S adsorption, while the Eg value of Mg12O12 nano-cage reveals higher sensitivity to H2S than SO2 adsorption. The molecular dynamic calculations show that the H2S molecule cannot be retained at the surface of a Be12O12 nano-cage within 300–700 K and cannot be retained on a Mg12O12 nano-cage at 700 K, while the SO2 molecule can be retained at the surfaces of Be12O12 and Mg12O12 nano-cages up to 700 K. Moreover, the thermodynamic calculations indicate that the reactions between H2S as well SO2 with Be12O12 and Mg12O12 nano-cages are exothermic. Our results suggest that we can use Be12O12 and Mg12O12 nano-cages as sorbents as well as sensors for H2S and SO2 gases.

DFT calculations at B3LYP/6-31 g(d,p) with the D3 version of Grimme's dispersion are performed to investigate the application of TM-encapsulated Mg12O12 nano-cages (TM = Mn, Fe, and Co) as a hydrogen storage material. The molecular dynamic (MD) calculations are utilized to examine the stability of the considered structures. TD-DFT method reveals that the TM-encapsulation converts the Mg12O12 from an ultraviolet into a visible optical active material. The adsorption energy values indicate that the Mn and Fe atoms encapsulation enhances the adsorption of H-2 molecules on the Mg12O12 nano-cage. The pristine Mg12O12 and CoMg12O12 do not meet the requirements for hydrogen storage materials, while, the MnMg12O12 and FeMg12O12 obey the requirements. MnMg12O12 and FeMg12O12 can carry up to twelve and nine H-2 molecules, respectively. The hydrogen adsorption causes a redshift for the lambda max value of the UV-Vis. spectra of the MnMg12O12 and FeMg12O12 nano-cages. The thermodynamic calculations show that the hydrogen storage reaction for MnMg12O12 nano-cage is a spontaneous reaction while for FeMg12O12 nano-cage is not spontaneous. The results suggested that the MnMg12O12 nano-cage may be a promising material for hydrogen storage applications.

DFT and TD-DFT calculations are employed to examine the adsorption of halogen atoms (F, Cl, and Br) and molecules (F2, Cl2, and Br2) on cobalt-doped porphyrin (CoP). The impact of an external static electric field (EF) on the adsorption and the UV–Vis spectra is studied. The adsorption of halogen atoms as well as F2 molecule is chemisorption in the range from −1.14 to −2.41 eV while the adsorption of Cl2 and Br2 is physisorption. The adsorbate–substrate interaction reduces the HOMO-LUMO gap (Eg) to be 1.79–2.72 eV compared to 3.11 eV for CoP. The EF controls the adsorption process where the positive EF improves the corrected adsorption energy (Eadscorr.) while the negative EF attenuates the Eadscorr.. Additionally, the positive EF leads to a decrease in the Eg while, the negative EF increases the Eg. Consequently, for sensing purposes, high sensitivity and low response time are expected for the CoP at the positive EF while negative EF encourages the desorption process and decreases the recovery time. The CoP is optically active with λmax of 494 nm. The UV–Vis spectra analysis shows that the adsorption of halogen atoms causes a blue shift of λmax to be 394, 488, and 491 nm while the adsorption of halogen molecules causes a red shift of λmax to be 892, 846, and 698 nm, respectively. The λmax for adsorbate–substrate complexes is affected by the EF. Our results declare that the cobalt-doped porphyrin may be utilized as a candidate sensor for the considered halogen atoms and molecules.

DFT-D3 and TD-DFT calculations at B3LYP/6-311 + g(d) level of theory are employed to study the influence of the TM (Co and Ni) doping, the adsorption of CH3OH, and the external electric field (EF) on the electronic and optical properties of B12N12. The results are analyzed in point of view of BSSE corrected adsorption energies, the density of states (DOS), NBO atomic charges, and UV-vis spectra. The obtained values of dipole moment, ionization potential, chemical potential, hardness, and electrophilicity verified that the doped TM-boron nitride nano-cages are more reactive than the pure B12N12 nano-cage as well the TMB11N12 nano-cages are more reactive than TMB12N11 nano-cages. Additionally, the doping decreases the HOMO-LUMO gap energy gap to 55% and 30% and enhances the adsorption energy by 41.4% and 44.1% for CoB11N12 and NiB11N12 nano-cages, respectively. The adsorption of CH3OH reduces the HOMO-LUMO gap for the B12N12 and enlarge that for the TMB11N12. The value and the direction of the applied EF control the adsorption energy, sensitivity, response time, and recovery time. The TD-DFT calculations declare that the CH3OH adsorption on CoB11N12 and NiB11N12 under the influence of the EF causes considerable shifts for the lambda(max) value in the visible region. Thus, the obtained results may be fruitful for designing an electrical and optical sensor for CH3OH utilizing pure and doped boron nitride nano-cages.

The interaction between ammonia gas (NH3) and boron nitride nano-cage (B12N12) have been investigated under the effect of the surrounding media as well as the presence of external electric field using the B3lyp/6-31g(d) level of theory. In gas phase and water medium, the NH3 molecule was chemically adsorbed on B12N12 cluster with adsorption energy of -1.32 and -1.61 eV as well the HUMO-LUMO gap was lowered by 0.1 and 0.2 eV, respectively. An external electric field (EF) of intensity -1.028 up to 1.028 V/angstrom was applied. The negative values of the EF gradually enhance the adsorption energy to be -2.80 and -3.71 eV while the positive values of the EF gradually inhibit the adsorption energy to be -0.21 and -0.01 eV for gas phase and water medium, respectively. In addition, the presence of the EF noticeably affect the dipole moment, and the HOMO-LUMO energy gap. Our results may be useful for B12N12 applying as NH3 detector or removing material in either gas phase or water medium.

The DFT-D3 and TD-DFT calculations at B3lyp/6-311+g(d) level of the theory have been employed to study the impact of TM (TM = Mn, Fe) doping as well as the adsorption of CO, NO, and NH3 gases on the electrical and optical properties of the boron nitride nano-cage (B12N12). The binding energy, ionization potential, electron affinity, chemical hardness, and softness are estimated to emphasize the stability of the doped MnB11N12 and FeB11N12. The band gap for B12N12 is 6.748 eV while the Mn and Fe doping decrease its value to 2.199 and 2.333 eV, respectively. In addition, the doping increases the dipole moment and enhances the adsorptivity of the clusters as well as converts B12N12 from UV active material (lambda(max)=195 nm) into visible active material (lambda(max)=389 nm for Mn and 419 nm for Fe). Second order perturbation theory analysis of donor-acceptor interactions in the NBO basis suggests the donation-back donation mechanism for the gas-cluster interaction. The adsorption of CO, NO, and NH3 gases causes a noticeable change in the E-g of MnB11N12 (-14.37%, +22.51%, +26.6%, respectively) while affects less the Eg of B12N12 and FeB11N12, as well as leads to a considerable shift to the lambda(max) of the UV-Vis spectra. These results may be helpful for designing a promising boron nitride gas sensor.

The density functional theory (DFT) at B3LYP/6-31 g(d) level of calculations is utilized to examine the effect of doping and co-doping as well as CH2O adsorption on the structural and electronic properties of boron nitride nano-cages. The adsorption properties of CH2O are analyzed in terms of adsorption energies (E-ads), charge transfer, the electrostatic potential (ESP), and the density of states (DOS). Our results show that the CH2O is chemically adsorbed via its oxygen atom on the boron and beryllium sites of pristine and doped as well as co-doped boron nitride nano-cages. The E-ads was -0.402 eV for the pristine B12N12 nano-cage, while the doping enhances the E-ads to be -0.981, -1.219, and -1.138 eV for doped BeB11N12, CB11N12, and co-doped Be2B10N12 nano-cages, respectively. The interaction between the CH2O molecule and the considered nano-cages depends on the ESP around the adsorbing sites. In addition, the interaction between the CH2O molecule and the nano-cages undergoes by the donation-back donation mechanism. The adsorption of the CH2O molecule reduces the HOMO-LUMO gap for the pristine B12N12 by 49 % and for the doped for CB11N12 nano-cage by 22 %, meanwhile, the most decrease is 55 % recorded for the co-doped C2B11N11 nano-cage. Therefore, the adsorption of CH2O affected the electrical conductivity for the pristine and doped as well as co-doped BN nano-cages. The present results proposing that the considered doped boron nitride nano-cages could be a promising material for CH2O gas removal and detection.

In this work, we report a combined experimental and theoretical study of aluminum phthalocyanine chloride (AlPcCl). The FT-IR and Raman spectra of AlPcCl were recorded and analyzed. The density functional theory (DFT) computations have been performed at B3LYP/6-31g and B3LYP/6-311g to derive equilibrium geometry, vibrational wavenumbers, intensity and NLO properties.All the observed vibrational bands have been discussed and assigned to normal mode or to combinations on the basis of our DFT calculations as a primary source of attribution and also by comparison with the previous results for similar compounds.The natural bond orbital (NBO) calculations were performed to study the atomic charge distribution of the investigated compound. The calculated results showed that dipole moment of the investigated compound was 4.68 Debye and HOMO-LUMO energy gap was 2.14eV. The lowering of frontier orbital gap appears to be the cause of its enhanced charge transfer interaction.

The adsorption of CO, CO2, NO and CO2 gas molecules on different chiralities of single boron nitride nanotubes (BNNTs) is investigated, applying the density functional theory and using basis set 6 - 31 g (d,p). The energetic, electronic properties and surface reactivity have been discussed. We found that the best BNNT for adsorbing the CO, CO2, NO and NO2 gas molecules is (5,0) BNNT with adsorption energy of -0.27, -0.37 eV, -0.23 and -0.92 eV, respectively. Also, the electronic character of (5,0), (9,0), (5,5) and (6,6) BNNTs is found to be not affected by the adsorption of CO, CO2, NO and NO2 gas molecules. It is found that the dipole moments of zig-zag (5,0) and (9,0) BNNTs are always higher than the arm-chair (5,5) and (6,6) BNNTs. Also, it is noticed that the highest dipole moment is for (9,0) BNNT.

Using density functional theory, the adsorption of CO, CO2, NO and CO2 gas molecules on different chiralities and diameters of single carbon nanotubes is investigated in terms of energetic, electronic properties and surface reactivity. We found that the adsorption of CO and CO2 gas molecules is dependent on the chiralities and diameters of CNTs and it is vice versa for NO and NO2 gas molecules. Also, the electronic character of CNTs is not affected by the adsorption of CO and CO2 gas molecules while it is strongly affected by NO and NO2 gas molecules. In addition, it is found that the dipole moments of zig-zag CNTs are always higher than the arm-chair CNTs. Therefore, we conclude that the zig-zag carbon nanotubes are more preferred as gas sensors than the arm-chair carbon nanotubes, especially for detecting NO and NO2 gas molecules.

The adsorption properties and characteristics of CO on Cu, Ag and Au atoms deposited on various sites of the alkaline earth oxide MgO and BaO. The three members of morphological irregularities, terrace, edge, and oxygen terminated corner of MgO and BaO (001) surface have been studied by means of density functional calculations and embedded cluster model. The examined clusters were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces. The  adsorption  properties  of  CO  have  been  analyzed  with reference  to  the  nature  of  the  oxide  support,  pairwise  and  non-pairwise Please read the full paper.

In the present work, a computational study for the optimized molecular structural parameters, thermo-chemical parameters, total dipole moment, HOMO-LUMO energy gap and a combined experimental and computational study for FT-IR spectra for 2-(2-furanylmethylene) propanedinitrile have been investigated using B3LYP utilizing 6-31G and 6-311G basis set. Our calculated results showed that the investigated compound possesses a dipole moment of 7.5D and HOMO-LUMO energy gap of 3.92eV using B3LYP/6-311G which indicates that our investigated compound is highly applicable for photovoltaic solar cell applications.

Au/2-(2-furanylmethylene) propanedinitrile/p-Si heterojunction was fabricated using conventional thermal evaporation technique. Current density-voltage (J-V) characteristics of the heterojunction were investigated at different temperatures. Tunneling conduction mechanism in the lower voltage range was identified from the forward bias (J-V) characteristics. The calculated value of the change of built-in voltage with respect to the absolute temperature is (-1.88 x 10(-3) V K-1). At higher voltages, a space charge limited current (SCLC) mechanism controlled by an exponential trapping distribution above the valence band edge was observed. The total concentration of traps was found to be 8.077 x 10(21) m(-3). Under reverse bias, the conduction mechanism is due to thermally generated carriers in the lower voltage range and the Poole-Frenkel effect is observed in the higher voltage range. The heterojunction showed a photovoltaic behavior under illumination with an open-circuit voltage of 0.19 V and a short-circuit current density of 102.7 mA m(-2). (C) 2013 Elsevier B.V. All rights reserved.

The interactions of nitrogen dioxide molecule (NO2) on Au atom adsorbed on the surfaces of metal oxide MgO (100) on both anionic (O2-) and defect (F-s and F-s(+)-centers) sites have been studied using the Density Functional Theory (DFT) in combination with embedded cluster model. The adsorption energies of NO2 molecule (N-down as well as O-down) on O-2, F-s and F-s(+)-sites were considered. Full optimization for the additive materials and partial optimization for MgO substrate surfaces have been done. The formation energies were evaluated for F-s and F-s(+) of MgO substrate surfaces. Some parameters, the Ionization Potential (IP) and electron Affinity (eA), for defect free and defect containing surfaces have been calculated. The interaction properties of NO2 have been analyzed in terms of the adsorption energy, the electron donation (basicity), the elongation of N-O bond length and the charge distribution by using Natural Bond Orbital (NBO) analysis. The adsorption properties were examined by calculation of the Density of State (DOS). The presence of the Au atom increases the surface chemistry of the anionic O2--site of MgO substrate surfaces. On the other hand, the presence of the Au atom decreases the surface chemistry of the Fs and F-s(+)-sites of MgO substrate surfaces. Generally, the NO2 molecule is strongly adsorbed (chemisorption) on the MgO substrate surfaces containing F-s and F-s(+)-centers.