Studies have shown that fluvoxamine can be useful in preventing the spread of Covid-19 disease (in the early stages of the disease) by strengthening the body’s immune system. For this purpose, in this work, the structural and electronic properties of fluvoxamine drug were investigated using quantum theory of atom in molecule (QTAIM) and Density-functional theory (DFT) at B3LYP-DFT/6-311G+ (at presence of water as solvent and the CPCM model) computational level. Also, in order to improve the electronic/pharmaceutical properties, the effect of electron donor/acceptor groups of NO2 and NH2 on fluvoxamine was studied. According to the results, electronic properties changed significantly in the presence of the NO2 group. So that (in the presence of NO2) cohesive energy, energy gap, dipole moment, adsorption energy, antioxidant properties, and recovery time improved by 20%, 70%, 84%, 48%, 48%, and 46% respectively. Although the electronic properties were improved in the presence of the NH2 group, the effect of the NO2 functional group was more noticeable. Therefore, it is expected that the presence of the NO2 electron-acceptor electron group will improve its medicinal function by changing the electronic properties of the drug fluvoxamine.

A search has been conducted, employing ab initio molecular orbital theory, for potential tetrel-bonded complexes between the fluorinated methanes methyl fluoride, difluoromethane and fluoroform, and the related hydrides ammonia, water, hydrogen fluoride, phosphine, hydrogen sulfide and hydrogen chloride. Eleven such complexes have been identified, six containing CH3F and five CH2F2. The complexes are typically less strongly bound than their hydrogen-bonded counterparts, and the interaction energies vary in a consistent way with the periodic trend of the electron donors. The intermolecular separations and changes of the relevant intramolecular bond lengths, the wavenumber shifts of the critical vibrational modes, and the extents of charge transfer for the atoms most closely involved in the interactions correlate, by and large, with the strengths of interaction.

By employing the Nikiforov-Uvarov functional analysis (NUFA) method, we solved the radial Schrodinger equation with the shifted Morse potential model. The analytical expressions of the energy eigenvalues, eigenfunctions and numerical results were determined for selected values of the potential parameters. Variations of different thermodynamic functions with temperature were discussed extensively. Different quantum information theories including Shannon entropy, Fisher information and Fisher-Shannon product of the shifted Morse potential were investigated numerically and graphically in position and momentum spaces for ground and first excited states. The quantum information theories considered satisfied their corresponding inequalities including Bialynicki–Birula–Mycielski, Stam–Cramer–Rao inequalities and the Fisher–Shannon product relation.

Possible theoretical basis for the hypothesis of prohibition of some electron configurations in atoms and molecules presented by one of the authors earlier is considered. Existence of such prohibited configurations follows from the wave function antisymmetry of atoms and molecules. Our hypothesis is as follows: the configurations, in which the potentials of any two electrons with the same spins are equal, are forbidden. If the hypothesis comes true, it will be possible to find the nodal surfaces of many-electron wave functions for atoms and molecules analytically a priori.

A series of cyclometalated platinum(II) complexes with aromatic ligands, such as pyridyl, pyrimidinyl and pyrazolate, were investigated with theoretical calculations. To investigate the relationship between ligands with molecular orbital, molecular rigidity, electroluminescent properties and spectroscopic properties, the electrostatic potential (ESP), density-of-states (DOS), root mean squared displacement (RMSD) were calculated. On the basis of calculated absorption and phosphorescence data, the analysis of “hole” and “electron” have also been performed. From the RMSD calculations, complex 3 shows significant structural distortions on S1 state and it may be applied in thermal activation delayed fluorescence (TADF) materials. The electroluminescent properties calculations show that complex 1 is suitable for hole transport material and complex 4 can be applied in electron transport material.

Half heusler compounds have gained attention due to their excellent properties and good thermal stability. In this paper, using first principle calculation and Boltzmann transport equation, we have investigated structural, electronic, mechanical and thermoelectric properties of PdXSn (X=Zr,Hf) half Heusler materials. These materials are indirect band gap semiconductors with band gap of 0.52 (0.44) for PdZrSn (PdHfSn). Calculations of elastic and phonon characteristics show that both materials are mechanically and dynamically stable. At 300K the magnitude of lattice thermal conductivity observed for PdZrSn is 15.16 W/mK and 9.53 W/mK for PdHfSn. The highest ZT value for PdZrSn and PdHfSn is 0.32 and 0.4 respectively.

Hydrogen reduction of tungsten oxide is currently the most widely applied ultrafine tungsten powder production process. The process has the advantage of short, pollution free and simple production equipment. But it is difficult to effectively control the morphology and particle size of the tungsten powder because of lacking in-depth understanding of the dynamic mechanism of the process. The first-principles calculations are carried out to explore the diffusion and internal adsorption of hydrogen on the WO-terminated surface of WO3 based on the density functional theory. The results show that hydrogen can diffuse from the WO terminal surface to the inside of WO3, the activation energy of diffusion is 46.682 Kcal/mol. It’s preferable for hydrogen to diffuse from the surface to the inside than diffuse within the WO3 lattice. The adsorption energy of hydrogen on the WO termination surface of WO3 is 15.093 Kcal/mol, the adsorption energy of hydrogen inside the WO termination surface of WO3 is 14.116 Kcal/mol, which means the hydrogen is easier to adsorb inside the WO3 lattice.

Quantum chemical calculations have been performed on B3 ring stabilized Y-Y interaction (Y = Be, Mg, Ca) to understand the possibility of binuclear sandwich type complex formation. Calculations indicate single reference character of the studied systems. The complexes have been found to be stable towards dissociation into different fragments. Thermodynamic consideration also indicates the favourability of their formation. Increase in aromaticity of the parent B3 ring upon complexation is observed which is expected to provide extra stability to the complexes.

A two-sublattice decorated Blume-Capel ferrimagnet has been investigated using the mean field theory. Interesting behaviors of long-range order are obtained depending on particular magnitudes of magnetocrystalline anisotropies for both sublattices sites. Distinguishable features have been discovered in two-dimensional decorated lattice consisting of spin-5/2 and decorating spin-7/2 ions on the bonds. It is found the present system shows two ferrimagnetic compensation temperatures. However, one compensation temperature for different or fixed values of decorated magnetic anisotropies with the values of J1=-0.5 , J2=-1.0 , or with J1=-1.0 , J2=-0.5, has been induced, respectively. The magnetization behavior in the (M,DB/IJ2I) space has not already been considered showing the crystalline anisotropy dependence of total magnetization remanences. Besides, the variations of net magnetizations versus the decorated crystal fields, i.e., in the(M,DA/IJ2I) space, have been done, with J1=-0.5, J2=-1.0 , for various values of T=2.0, 2.5,3.0 , respectively.

In a recent experimental investigation, the chlorination of the highly efficient Y6 fluorinated molecule improved up to 16.5 \% the power conversion efficiency of an organic solar cell. To understand the better performance of BTP-4Cl:PBDB-TF acceptor-donor combination in comparison with BTP-4F:PBDB -TF in the newly reported organic solar cell, DFT calculations were performed in order to obtain a diversity of parameters related to molecular proper ties, such as electroacceptance, electron energy levels, absorption spectrum, charge mobility, and kinetics in exciton dissociation/recombination processes. Interestingly, chlorination improves charge mobility and the capacity to accept electrons. The binding energy is lower for the chlorinated than the fluorinated molecule, revealing an easier exciton cleavage in the former. Absorption spectra are in line with experimental ones, suggesting an ex cellent donor-acceptor complementarity. Additionally, novel molecules were proposed taking into account synthesized compounds, and the same parameters were analyzed. Results showed exciting behavior for the theoretically suggested compounds. Many properties were improved with the proposed molecules, which can also be exploited in solar photocells. Although it is a challenge to simulate/model a complete photoactive layer of an organic solar cell, it is proved through electronic structure calculations that the properties of the materials involved in the photovoltaic device can be obtained. In this way, give some light on the power conversion efficiency comparison and propose new compounds.

A mechanism for the reaction of diformylhydrazine with o- and p-aminophenols has been studied by quantum-chemical calculations within the framework of electron density functional theory using the B3LYP/6-311++G (d,p)//B2PLYP/6-311++G (d, p) basis sets. It is shown that the first stage of this reaction involves nucleophilic addition of the aminophenol nitrogen to one of the carbonyl groups of diformylhydrazine to afford an unstable geminal amino alcohol, which can be further dehydrated to iminohydrazide or hydrazonamide. The prototropic imino-amine rearrangement occurring in the iminohydrazide delivers hydrazonamide, The latter, owing to nucleophilic attack of the nitrogen atom at the second carbonyl group, is converted into a cyclic amino alcohol, dehydration of which produces the target 1,2,4-triazole. The obtained results have been compared with the data NMR spectroscopy.

Structures, stabilities, and interactions of AuX (X = C - Pb) series are theoretically investigated at CCSD(T) and B3LYP levels with extend basis sets. Natural bond orbital analysis shows that the Au-X interaction is resulted by the overlap of sp hybrid on X and 6s5d hybrid on Au atom. Laplacian and total electronic energy density values at BCP shows the “intermediate type” of Au-X (X = Si, Ge, Sn, Pb) interactions and covalent type of Au-C interaction. Moreover, analysis of electron density deformation shows pronounced charge accumulation in the middle of the region between lighter X and Au, suggesting obvious covalent character of interaction. ELF shows increased covalency from X = Pb to X = C. Energy decomposition analysis shows positive steric contribution and negative quantum contributions to the Au-X interactions. Comparing the interaction energy of AuC with other AuX series, the decrease of interaction strength between them is caused by the positive contribution of steric effect and the negative contribution of quantum and electrostatic effects. Steric charge distribution shows interaction type causes effects to distribution of steric charge. And steric energy is correlated positively with the total interaction energy and correlated positively with the steric charge deformation at BCP.

Monomeric-to-Pentameric Aggregation of Molecular Cs4PbBr6 Halide Perovskite: a First-Principles Investigation

Herein, we report the mechanism of Ir(III)-catalyzed intermolecular branch-selective allylic C−H amidation, including the influence of substituent effect on yield and regioselectivity. The sequence of amidation reaction is alkene coordination, allylic C−H activation, oxidative addition of methyl dioxazolone, reductive elimination of allyl-Ir-nitrenoid complex, amine protonation and proto-demetallation. The apparent activation energy of amidation between hexene and methyl dioxazolone is 17.8 kcal/mol, and the energy difference between two transition state for formation amide is only 2.8 kcal/mol. The introduction of more electron-deficient groups at the allyl terminal increases the apparent activation energy, conversely, the introduction of electron-donating groups significantly reduces the apparent activation energy. Among them, the apparent activation energy of the reaction between aniline group substituted allyl and methyl dioxazolone is only 13.8 kcal/mol, which further improves the reaction yield. In addition, the introduction of more electron-withdrawing groups on dioxazolone can significantly improve the regioselectivity. When 3,4,5,-trifluorophenyl substituted dioxazolone and hexene occur C−N bond coupling reaction, the energy difference of the two transition states is as high as 9.0 kcal/mol, indicating that the regioselectivity is greatly improved. The mechanism explanation of allylic C−H amidation will provide strong theoretical support for streamlined synthesis of allyl branched amides.

A small molecule probe for simultaneous detection of HSA and SO2 via their distinct fluorescent signals was designed recently. This effective tool provided a significant boost in understand underlying mechanism of synergistic action between SO2 and HSA in disease. The structure and fluorescent character of this probe molecule were studied under density functional theory in this work. The different stable conformations of probe C23 were found through theoretical method which explained the no experimental fluorescent character of the probe itself. The electron excitation analysis indicated the charge transfer process in the restricted C23 (binding to the hydrophobic cavity of HSA) and CS (C23 reaction with SO2) when the molecules were under optical excitation. The theoretical results could be helpful for understanding the electronical properties in the probe and providing the insights for designing new probe molecules.

We examine above-threshold ionization spectra of model atomic hydrogen in short infrared laser pulses by solving the one-electron time-dependent Schr\“odinger equation in momentum space. To bypass the difficulty of solving the time-dependent Schr\”odinger equation with the interacting nonlocal Coulomb potential, we have recently formulated an alternative \emph{ab initio} approach [Ongonwou et al. Annals of Physics {\bf 375}, 471 (2016)], which is relied on the expansion of the atomic wavefunction and the interacting nonlocal Coulomb potential on a discrete basis set of Coulomb Sturmians in momentum space. As far as short infrared laser pulses are concerned, we have numerically evaluated the photoelectron momentum distributions, angular distributions and bound states populations. The results obtained from our accurate new computationally method are compared against predictions of other time-dependent calculations in the literature. This new theoretical model shows its sensitivity to the carrier-envelope phase of the laser pulse and captures the left-right dependence of the emitted photoelectrons momentum and angular distributions. More precisely, short pulses manifest significant dependence of the differential ionization probability on carrier-envelope phase of the laser pulse and broken forward-backward symmetry in the angular distributions.

In the present work, the cubic structure of HgF2 has been studied using generalized gradient approximation within the framework of density functional theory. Here, the positive phonon frequencies in the phonon dispersion curves show stability of the structure. The elastic constants also satisfy criteria of being kinetically stable material. The B/GH ratio 2.56 of HgF2 indicates its ductile nature. The thermodynamic intrinsic parameters of HgF2 have been calculated using linear response method where the temperature variations of Helmholtz free energy (F), internal energy (E), specific heat at constant volume (Cv) and Debay temperature (ϴD) have been studied. The explanation of the bonding nature is discussed using electronic band structure, density of states and charge density. Here, the presence of the wide valence band gap in electronic band structure and density of states displays the ionic behaviors of HgF2. In addition, the charge density along the [111] plane defines hybridization in between ‘s’, ‘p’ and ‘d’ orbitals in HgF2. The optical parameters of Fm3m-HgF2 were calculated using Random Phase Approximation. Here, the found static refractive index is 1.26. The general optical study showing the trend of being transparent in most of the UV region and fully transparent in the visible region by ionic Fm3m HgF2. Also, it shows significant absorption in the entire UV region and a long absorption tail which extends into the visible region.

In this paper, we study the structural, electronic and optical properties of the inorganic solar perovskites XPbBr3 (X= Li or Na). We applied the two methods: the density functional theory (DFT) and time-dependent density-functional theory (TDDFT). In fact, we performed the DFT method using the Quantum Espresso package. Also, the total energies of the studied inorganic solar perovskites XPbBr3 (X= Li or Na) have been deduced as a function of the lattice parameter a (Å). The two calculation methods have been carried out under the GGA-PBE and GGA-PBESol approximations. Moreover, the total and partial density of states (DOS) and the band structure of the studied compounds have been presented and discussed for the two cases: with and without the spin orbit coupling (SOC) approximation. In addition, the DFT and TDDFT have been explored in order to elaborate the structural, the electronic and the optical properties of the inorganic perovskite CsPbI3 material for solar cell applications. When using the GGA-PBESol method without SOC approximation, we found a band gap energy value greater than that one computed when adding the SOC correction. On the other hand, the optical properties of the studied material have been studied. In particular, we found that the inorganic solar Perovskite XPbBr3 (X=Li or Na) materials exhibit a high transparency of the electromagnetic radiations in energy range between 0 eV and 33 eV.