The ab initio molecular dynamics simulations are performed to study the atomic structures of Co92-xBxTa8 (x = 30, 32.5, 35, 37.5, at.%) glassy alloys. The result shows that the local packing of B-centered clusters is more efficient than that for Co- and Ta-centered clusters. It is also found that B-centered clusters are the primary structure-forming clusters. The Kasper polyhedra with a Voronoi index of <0 3 6 0> and <0 2 8 0> are dominant in B-centered clusters. Specially, the <0 3 6 0> clusters can form a robust network structure, which plays a key role in mechanical properties. Such a network structure has a higher activation barrier for structural rearrangement and a better resist to plastic flow. Thus, the increase in the fraction of <0 3 6 0> with B content would result in an increase in yield strength as well as a sharp decrease in compression plasticity.

The influences of the initial states of HCl on the stereodynamics properties of the Ca+HCl reaction are investigated by utilizing the method based on the quasi-classical trajectory (QCT) theory and the analytical potential energy surface (APES). The orientation and alignment behaviors for the rotational angular momentum of the product, along with the generalized differential cross-section (PDDCS) dependent polarization, are employed to explore the stereodynamics properties. The initial rotational states of the HCl molecule impose a remarkable affection on the vector correlation distributions, regardless of the orientation, alignment, or PDDCS. The obvious forward or backward scattering, as well as the weak sideway scattering phenomena, are found for the different initial rotational states of the HCl molecule. The initial higher rotational-excited state of j=3 results in more obvious stereodynamics effects.

The Shannon entropy (S) and the Fisher Information (I) entropies are investigated for a generalized hyperbolic potential in position and momentum spaces. Firstly, the Schrodinger equation is solved exactly using the Nikiforov-Uvarov-Functional Analysis (NUFA) method to obtain the energy spectra and the corresponding wave function. By Fourier transforming the position space wave function, the corresponding momentum wave function was obtained for the low lying states corresponding to the ground and first excited state. The positions and momentum Shannon entropy and Fisher Information entropies were calculated numerically. Finally, the Bialynicki-Birula and Mycielski (BBM) and the Stam-Cramer-Rao inequalities for the Shannon entropy and Fisher Information entropies respectively were tested and was found to be satisfied for all cases considered

Analytic first and second derivatives of the energy are developed for the fragment molecular orbital method interfaced with molecular mechanics in the electrostatic embedding scheme at the level of Hartree-Fock and density functional theory. The importance of the orbital response terms is demonstrated. The role of the electrostatic embedding upon molecular vibrations is analyzed, comparing force field and quantum-mechanical treatments for an ionic liquid and a solvated protein. The method is applied for 100 protein conformations sampled in MD to take into account the complexity of a flexible protein structure in solution, and a good agreement to experimental data is obtained: frequencies from an experimental IR spectrum are reproduced within 17 cm$^{-1}$.

The defected carbon materials as a metal-free catalyst shown superior stability and catalytic performance in the acetylene hydrochlorination reaction. Through DFT calculation, for the first time several different defected configurations comprising mono, di-vacancies, and Stone Wales defect on single-walled carbon nanotubes (SWCNTs) have been used as a direct catalyst for acetylene hydrochlorination reaction. These defective sites on SWCNTs are the most active site for acetylene hydrochlorination reaction compared to pristine SWCNT. The different configuration of defects have different electronic structure, which specify that mono-vacancy defect, have more states adjecent to the Fermi level. The reactant acetylene (C2H2) adsorbed strongly than hydrogen chloride (HCl) and expected to be the initial step of the reaction Acetylene adsorbed strongly at mono-vacancy defected SWCNT compared to other investigated defects. The reaction pathways analysis revealed that mono- and di-vacancy defected SWCNT has a minimum energy barriers and shows extraordinary performance towards acetylene hydrochlorination. This work suggests the potential of metal-free defected carbon to catalyze acetylene hydrochlorination and provide a solid base for future developments in acetylene hydrochlorination.

The internal disorder of the two-dimensional confined hydrogenic atom is numerically studied in terms of the confinement radius for the 1_s_, 2_s_, 2_p_ and 3_d_ quantum states by means of the statistical Crámer-Rao complexity measure. First, the confinement dependence of the variance and the Fisher information of the position and momentum spreading of its electron distribution are computed and discussed. Then, the Crámer-Rao complexity measure (which quantifies the combined balance of the charge concentration around the mean value and the gradient content of the electron distribution) is investigated in position and momentum spaces. We found that confinement does disentangle complexity of the system for all quantum states by means of this two component measure.

Complete vibrational assignments have been performed for free base, cationic and hydrochloride species derived from antiviral adamantadine by combination of hybrid B3LYP with the 6-31G* and 6-311++G** basis sets and the SQMFF methodology. Normal internal coordinates and scaling factors were used to obtain the harmonic force fields and scaled force constants of three species in gas phase and in aqueous solution. Bond lengths and angles of cationic and hydrochloride species show very good concordances with the experimental of amantadinium azide. The cationic species reveals higher solvation energy value, as compared with antiviral agents, however, brincidofovir, the antiviral used to ebola disease presents a higher reactivity against to adamantadine. Positive value of Mulliken charge on N1 of hydrochloride species in solution could justify the ionic character of H29•••Cl30 bond, as evidenced by bond order and AIM calculations. The hydrochloride species is the most reactive in both media while the cationic species the less reactive. High electrophilicity and nucleophilicity indexes of cationic species in both media justify its higher hydration. Good concordances were observed between experimental and predicted 1H and 13C NMR and electronic spectra. In solution, the three species are present as revealed by the experimental UV spectrum of hydrochloride amantadine

In this study, three novel sensitizers with the donor-acceptor-π-spacer-acceptor D-A’-π-A) structure were designed based on the benzothiadiazole (BTD) surrounded by two thiophenes in each side (T4) mono-functionalized by an acid phosphonic (A) T4BTD-A dye by insertion of vinyl and cyanide CN electron-withdrawing moiety in a different position. Their geometrical, electronic and photovoltaic parameters were predicted using density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations, via the functional BHandH in combination with the Poples basis set 6-311G(d) for small atoms and pseudo-potential basis set LANL2DZ for Titanium atom at the chloroform solvent medium via the implicit CPCM model. Results showed that the inclusion of the C=C and the CN moieties exhibits a decrease in the HOMO–LUMO gap, and a redshift in the absorption spectra. The photoelectric conversion efficiency (PCE) for the T4BTD-A dye was estimated to be about 6.57 % under the standard AM 1.5G solar radiation, which is in excellent agreement with its measured value of 6.40 %, suggesting that our calculations scheme is consistent. Moreover, the predicted PCE value after elongation of T4BTD-A by C=C and CN has increased to 7.11 % and (7.82 %, 8.09 %) respectively. Our results revealed that the addition of CN electron-withdrawing moiety enhances the PCE of the studied dyes, while the position of CN moiety has a slight effect on the PCE of the studied dyes. Additionally, our calculation suggests that the CCCN1 and CCCN2 are good candidates as efficient sensitizers for dye-sensitized solar cell DSSCs applications.

We calculate the concerted pathway of 1, 2-bromochloroethane monocation to C2H4+ and BrCl using the Minnesota density functional M06-2X and the def2-TZVP basis set. We also calculate the elimination channel of 1, 2-bromochloroethane monocation to C2H4 and BrCl+ for the reason that positive charge can be assigned to either moiety in the fragmentation process of 1,2-C2H4BrCl+. Our results demonstrate that the elimination channel of 1, 2-bromochloroethane monocation to C2H4+ and BrCl is preferred, and the singly charged 1,2-bromochloroethane ions surpass two energy barriers and then separate into C2H4+ + BrCl by an asynchronous concerted process. Experimentally, we confirm that this elimination channel is from the dissociative ionization process of 1,2-bromochloroethane monocation by dc-slice imaging technique. Besides, we can see in laser-induced time-of-flight mass spectra of 1,2-bromochloroethane that fragment ion C2H4+ occur at the laser intensity of 6.0×1013 W/cm2 while BrCl+ occur at a higher laser intensity, which is consistent with the theoretical results that appearance energy of ion C2H4+ should be lower than that of BrCl+, and this is the reason why the low-velocity component of ion BrCl+ is absent from our sliced images.

The structure, energetic and quantum chemical descriptors of Cs+ complexes of calix[4]arene-crown-6 (C4C6) and substituted C4C6 i.e 1,3 alternate-diethoxy C4C6 are reported here based on the analysis of results using density functional theory. Substitution of benzo group to both C4C6 and 1,3 alternate-diethoxy C4C6 resulted in reduction of binding energy (BE). Further substitution on benzo group with methyl, methoxy and amino groups leads to increase in BE and nitro substitution leads to decrease in BE for C4C6, whereas in the case of 1,3 alternate-diethoxy calix[4]arenebenzocrown-6, methoxy substitution leads to highest BE compared to other complexes. The calculated Gibbs free energy, ΔGgas also followed the same order as BE in the case of 1,3 alternate-diethoxy C4C6 and their substituted ligands. Furthermore, the ΔG of complexation were computed using thermodynamic cycle with conductor like screening model (COSMO) in different solvents: toluene, chloroform, octanol and nitrobenzene. The values of ΔGext are found to be increased with increase in the dielectric constant of the solvent and found to be highest in the nitrobenzene. The Atoms in Molecule (AIM) analysis reveals partial ionic character in Cs-O bond. Among all the studied complexes, 1,3 alternate-diethoxy calix[4]arene 3’-methoxy benzo crown-6 displays highest ΔGext in nitrobenzene. The calculated value of ∆∆Gext (∆∆G= ∆GCs+-∆GNa+) is found to be -41.82 kcal/mol with 1,3 alternate-diethoxy calix[4]arene 3’-methoxy benzocrown-6 which is higher than that obtained with calix [4] bis-crown-6 (-5.24 kcal/mol). The newly designed ligand might be suitable for the selective extraction of Cs+ over Na+ in the reprocessing of nuclear waste and thus invites the experimentalists for testing this DFT finding in the laboratory.

The mechanisms of C−C activation of 1-Benzylcyclopropan-1-ol to produce 1,6-diketone have been investigated by density functional theory (DFT) calculations. The catalyst [Cp*RhCl2]2 and additive Ag2CO3 play an important role in controlling the selectivity. By employing [Cp*RhCl2]2 as catalyst and Ag2CO3 as additive, the product is 1,6-diketone, whereas the β-hydride elimination product could not be obtained. The product would become monoketone in the absence of [Cp*RhCl2]2. In addition, the combination of catalyst [Cp*RhCl2]2 and additive AgOAc would also lead to monoketone. The observed selectivity could be attributed to the electronic effect.

To cope with the energy crisis and global warming issues, researcher are rendering their efforts and paying their attentions to analyze and fabricate hydrogen storage devices. In this regard, we report a comprehensive study on the structural, vibrational, and optoelectronic properties of Lithium Borohydride (LiBH4), a hydrogen storage material. For this purpose, calculations of structural properties have been made using the local, non-local and hybrid functionals within the framework of density functional theory (DFT). The lattice constants for the orthorhombic phase are determined by applying LDA, PBE and HSE06 density functionals and their results are compared with available experimental and theoretical studies. In order to determine IR and Raman active modes of vibrations, vibrational spectroscopy has been utilized through Density Functional Perturbation Theory (DFPT) approach. Li, B and H atoms are noticed to be contributing in the modes of vibrations between different ranges of frequencies, i.e., 0 to 400 cm-1, 1100 to 1300 cm-1 and 2250 -2400 cm-1. The respective values of band gaps are found to be 6.35 eV, 6.81 eV and 7.58 eV for LDA, PBE and HSE06 functionals, respectively, leading to indicate insulating nature of LiBH4 which makes it a promising candidate for applications in optoelectronic devices. The mechanical analysis reveals that LiBH4 is a brittle material. The optical properties such as dielectric constant, refractive index, reflectivity, absorptivity, conductivity and loss function are also calculated with the aid of well-recognized relation of Kramer-Kronig. The plasma frequency is noted at the highest peak (13.7 eV) of the energy loss function.

Minimum energy structures of neutral and radical cations of end substituted thia[n]helicenes (n=1-10) in DCM solvent are reported. For both neutral and radical cations of these helicenes, calculated structures are non-planar for n=3-10. Helical structures are obtained for higher helicenes and thia[8]helicene system has a helical structure with one complete turn. Equilibrium geometries are predicted applying B3LYP-D/6-311++G(d,p) method in conjunction with SMD solvent model. Single point energy calculations are also performed at MP2 level to improve certain energy parameters. Excited state calculations are performed using Time-Dependent Density Functional Theory (TDDFT) formalism to predict UV-Visible spectra of neutral and radical cations of thia[n]helicenes in DCM solvent. Thia[n]helicenes radical cation have strong absorption in the near IR region. Calculations also suggest that dimerization is not a favourable process in DCM solvent for the end substituted neutral and radical cation of thia[7]helicene. The present theoretical study examines the molecular and electronic properties of thia[n]helicenes in search of near infrared electronic devices.

The mechanisms of rhodium-catalyzed coupling reaction of ketoxime and 1,3-enynes were investigated by employing the density functional theory (DFT) calculations. Different 1,3-enynes would lead to different annulation products. Reaction A undergoes five sequential steps (C-H activation, 1,3-enyne migratory insertion, 1,4-Rh migration, cyclization, and deprotonation) to lead to [4 + 1] annulation product. Whereas, due to the electronic effect, the process generating [4 + 2] product in reaction A is restricted. In contrast, the electron-withdrawing group of N(Me)2 group in 1,3-enyne would bring about the [4 + 2] annulation product in reaction B. Our calculated results indicate that no [4 + 1] annulation product could be obtained in reaction C, in agreement with the experimental observation that the cis-allyl hydrogen in 1,3-enyne is crucial for the [4 + 1] annulation reaction.

Dirac relativistic partial wave analysis has been employed to analyze the angular distributions and critical minima along with maximum spin polarization for the elastic scattering of electrons from copper atoms over the energy range 1 - 2000 eV. Integrated elastic, inelastic, total and momentum transfer cross sections have also been calculated. This work uses a complex electron-atom optical potential that includes static, exchange, correlation-polarization and absorption potentials. Comparison of our calculations with the available experimental data and other theoretical calculations show a satisfactory agreement. As far as we are concern, critical minima and corresponding maximum spin polarization points have not yet been reported in literature.

A semiclassical phase-space perspective of band- and topological-insulator regimes of 2D Dirac materials, and normal- and superradiant-phases of atom-field interacting models is given in terms of delocalization, entropies, and quantum correlation measures. From this point of view, the low-energy limit of tight-binding models describing the electronic band structure of topological 2D Dirac materials like phosphorene and silicene with tunable band gaps, share similarities with Rabi-Dicke and Jaynes-Cummings atom-field interaction models, respectively. In particular, the edge state of 2D Dirac materials in the topological insulator phase exhibits a Schr\”odinger cat structure similar to the ground state of two-level atoms in a cavity interacting with a one-mode radiation field in the superradiant phase. Delocalization seems to be a common feature of topological insulator and superradiant phases.

Transition metal porphyrazines are a widely used class of compounds with applications in catalysis, organic solar cells, photodynamic therapy and nonlinear optics. The most prominent members of that family of compounds are metallophtalocyanines that have been subject of numerous spectroscopic and theoretical studies. In this work, the electronic structure and X-ray absorption characteristics of three Cu-porphyrazine derivatives are investigated by means of modern electronic structure theory. More precisely, the experimentally observed N K-edge and Cu L-edge features are presented and reproduced by time-dependent density functional theory, restricted open-shell configuration interaction and a restricted active space approach. Where possible, the calculations are used to interpret the observed spectroscopic features in terms of electronic transitions and furthermore connect spectral differences to chemical variations. Part of the discussion of the computational results concerns the impact of various parameters and approximations that enter the calculations, e.g. the choice of active space.

Photovoltaic properties of the natural dyes of chlorophylls consist of Chl a, Chl b, Chl c2, Chl d, Phe a, Phe y and Mg-Phe a, were studied in the gas phases and water. The extension of the π-conjugated system, the substitution of the central Mg2+ and proper functional groups in the chlorophyll structures can amplify the charge transfer and photovoltaic performance. Chl a shows more favorable dynamics of charge transfer than other studied chlorophylls. Chl d, Phe a, Phe y and Mg-Phe a, have a greater rate of the exciton dissociation in comparison with Chl a, Chl b, and Chl c2 originated from a lower electronic chemical hardness, a lower exciton binding energy, and a bigger electron-hole radius. As a result, better efficiencies of the light-harvesting and energy conversion of the chlorophylls mainly appear in the Soret band. The LHE values of the chlorophylls in water show that solvent favorably affects the ability of light-harvesting of the photosensitizers. Finally, based on the energy conversion efficiency, Chl a, Phe a, and Mg-Phe a, are proposed as the best candidates for using in the dye-sensitized solar cells.