A series of NN/NN bridged furazan energetic materials were designed. Physicochemical properties of the designed compounds were calculated based on the structures which were optimized by density functional theory (DFT) method at B3LYP/6-311G (d, p) level. The results indicate that the solid-phase heats of formation of the designed compounds were high which range from 1066.3 kJ mol−1(compound D4) to 2476.5 kJ mol−1 (compound C5). The N3 energetic was the most effective group to improve the heat of formation of the designed compounds while energetic group C(NO2)3 was the most effective unit to increases the density, heat of detonation, detonation velocity and detonation pressure. Finally, compounds C1, C2, C7 and F1 were screened as candidates of high energy density materials based on calculated detonation properties and sensitivities.

Utilizing the Molecular Electron Density Theory, to survey the [2+3] cycloaddition processes between 4-methyl-Benzonitrile-N-oxide (1) and 9α-hydroxyparthenolide (2), reaction, activation energies and the reactivity indices are determined. An examination of conceptual DFT indices, 9α-hydroxyparthenolide (2) will provide in this reaction as an eletrophile, whereas 4-methyl-Benzonitrile-N-oxide (1) will share as a nucleophile. The reaction and activation energies clearly demonstrate that this cyclization is regio- chemo and stereospecific, which is in perfect agreement with the outcomes of the experiment. The mechanism of this [2+3] cycloaddition follows two steps mechanism, as indicated by ELF analysis.

The present investigation covers structural, thermodynamics and vibrational spectroscopic study of tyramine neurotransmitter and its deprotonated form in the gas phase. The ab initio calculations on both the tyramine and its deprotonated form have been performed at DFT/B3LYP/6-31++G(d,p) level in order to optimize the electronic structures and computation of vibrational frequencies. Besides, the computed frequencies of tyramine and its deprotonated form have been compared with the experimentally reported IR and Raman frequencies which showed that most of the vibrational frequencies are in well agreement with earlier reported data. We have also documented the effect of hydrogen removal from the site of oxygen atom on the theoretically computed vibrational frequencies and geometrical parameters of tyramine. To explore the transition profile frontier bond orbitals energies have been computed. Moreover, natural bond orbital (NBO) calculations have also been performed to ensure stability of optimized electronic structures of tyramine and its deprotonated form.

The electronic structure and Li-ion diffusion properties of the surface of LiFePO4 (0 1 0) doped with C and B elements were investigated using a first-principles approach based on density universal function theory. Calculations of the formation energy show that the surface defect energy decreases after the dopant replaces the oxygen, which is in accordance with the thermodynamic stability criteria. The difference in charge density indicates that the doped atoms on the modified surface form stronger covalent bonds with adjacent Fe atoms, while the density of states study shows that the introduction of C and B elements narrows the forbidden band of LiFePO4 and exhibits better electronic conductivity. In addition, we calculate the energy barrier for the diffusion of Li-ions along the b-channel of the (0 1 0) surface using a transition state search method. The results show that the doped system possesses a lower energy barrier, which suggests that the doping of C and B elements reduces the limitation of Li-ion migration to the surface and increases the Surface diffusion rate. At the same time, we find that element B performs better than element C in improving surface conductivity and Li-ion surface diffusion .

The intramolecular Diels–Alder cycloaddition between cyclobutadiene and butadiene, which involves post-transition-state bifurcation (PTSB), has been investigated using the ring-polymer molecular dynamics (RPMD), classical MD and quasi-classical trajectory (QCT) simulations, and supervised machine-learning (ML) technique. The branching fraction of this reaction strongly depends on the simulation temperature. While QCT, classical MD and RPMD simulations performed at room temperature, starting from the ambimodal transition state (TS), showed the similar dynamics, QCT overestimated the minor branching fraction at low temperature. The supervised machine-learning analysis revealed that the initial coordinates and momenta for low frequency modes at the ambimodal TS contribute to the branching dynamics. The classical MD and RPMD methods follow similar conditions to quantum Boltzmann distributions, whereas the artificially localized phase distribution, considering that the zero-point energy is wedged into the classical particles. As a result, the QCT method can provide inadequate bifurcation dynamics, such as the overestimation of the minor product.

Glutathione (GSH) is the most abundant low-molecular-mass thiolated compound in plants and animals, highly relevant in humans since it is one of the principal antioxidant agents capable of scavenging reactive oxygen species (ROS). In addition, it has a function in the immune system and in cell proliferation, and most recently it was discovered that it works against COVID-19. Considering the high flexibility of glutathione, with an atomic configuration and charge state susceptible to minimal changes in its chemical environment, it is of relevance to ascertain what is the scavenging capacity of each of the most probable glutathione species under physiological conditions. In order to find the site and mechanism that contributes the most to the antioxidant activity of GSH, density functional theory (DFT) calculations on multiple species of this molecule were performed in this work. Reactivity indexes, related to hydrogen atom transfer (HAT), single electron transfer-proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) mechanism were calculated for glutathione. In addition, Gibbs free energies of reaction (ΔG) were obtained for the reactions of GSH with several free radicals to confirm the thermochemical viability of each antioxidant mechanism and to avoid misleading conclusions in terms of considering energetically unfavorable reactions. The results confirm that HAT is the chemical route contributing the most to the antioxidant activity of GSH. However, at least for one radical of interest, SPLET should also be considered.

The present study investigates the adsorption of three chemical warfare agent simulants (DMMP, CEES and paraoxon) on MgO and Ti-doped MgO nanotubes. Simulated annealing has been used to identify all low energy modes of adsorption. The study reveals that both DMMP and paraoxon interact with the metal oxide surface via their phosphoryl oxygens, but in the case of CEES, the adsorption via Cl is highly exothermic on the Ti-doped surface and results in the dissociation of the CCl bond. The effect of hydroxylation on the properties of the nanotube surface has also been investigated. The results reveal that as the number of water molecules attached to the nanotube is increased, the properties are also modified. Moreover, it is found that partial hydroxylation of the MgO surface favors maximal adsorption. This may be because complete hydration leads to blocking of all sites, hence the hydration should be partial, as the presence of a few hydroxyl groups assists the decomposition of the molecule.

Applied external potential and the exposed solvent condition have significant impact on the surface state of electrodes in electrochemical reactions. In this work, the grand canonical density functional theory (DFT) calculations were performed to systematically investigate the surface state and oxygen evolution reaction (OER) performances of the Ru (0 0 0 1) surface. Equilibrium Pourbaix diagrams demonstrated the oxidation state of either O* or OH*. Even in the negative polarized potential of USHE < 0.0 V, the Ru (0 0 0 1) surface exhibited the surface state of 1/9 ML O* preoccupying instead of the clean surface. Mechanistic studies of OER on the clean Ru (0 0 0 1) surface and Ru (0 0 0 1)O* (1/9 ML) surface revealed that in acidic OER process on clean Ru (0 0 0 1) surface, the oxygen coupling mechanism is more favorable than the nucleophilic attack mechanism involving OOH* intermediate formation.

Nowadays, owing to their potential applications in next-generation self-powered electronic devices, such as energy-harvesting smart garments from body movements and roll-up displays, electrochemical energy storages are enjoying considerable interest. Nonetheless, the development of such technologies has been hindered due to the rarity of high-efficacy electrodes with specific electrochemical performance. Amongst prospective electrodes, researchers have investigated 2D flexible and lightweight materials which have unique physiochemical attributes such as high conductance, high surface metal diffusivity, a hydrophilic surface and mechanical strength. Within this piece of research, a 2D orthorhombic di-boron di-nitride monolayer (o-B2N2ML), which is a boron nitride allotrope, was investigated. Moreover, several determining electronic chemical factors were investigated, such as theoretical capacity, equilibrium voltage and binding strength. Interestingly, the Mg-ion battery had a specific capacity of up to 1125 mAh.g-1. Also, the diffusion of Mg-ions was accelerated due to the presence of a o-B2N2 ring with a diffusion barrier (DB) of 0.26 eV. The low OCV and the low DB of the o-B2N2ML demonstrate that it can be used for practical purposes with long service life and fast rates of charge and discharge. The results also indicated the possible use of the o-B2N2ML as an anode material with high efficiency in MIBs.

Due to its thermochemical stability, CH4 is generally difficult to be dissociated. In this paper, the role of Sc atom in the results of the C-H bond activation operation was investigated using the DFT-D (M06-2X) method to understand the reaction process. It was discovered that the double low-spin state Sc atom easily react with CH4, whereas the high-spin ground state Sc is inert. The mechanism of the supported ScAl2O2- activated CH4 and the free Sc reaction system are extremely similar. The major channel is the low-spin state, displaying the incidence of spin flipping has an orbital drill-through effect. In the ScAl2O2- reaction, the Al2O2- anion can efficiently support Sc atom and thereby activate CH4 while also imparting its high reactivity to the supported Sc. In the future, it will be possible to examine the role of the Sc atom in the catalytic activation process of ScAl2O3- on CH4.

This study developed a new prediction model for hole injection barriers. Based on the electronegativity equalized model (EEM), the vacuum level shift in the adjacent layers was further considered in this model. In addition, the variation in ΦITO, which is dependent on the doping concentration of Sn, was considered as one of the determinants for predicting the hole injection barrier (HIB) between ITO and the organic layer. Further, the effect of p-dopants on the HTL energy level was also introduced in this model. The predicted HIBs of various anode/organic junctions were quantitatively and qualitatively consistent with UPS experiments. We believe that the developed EEM model can aid in determining the appropriate HTL/HIL organic materials without tremendous effort and time costs.

There is a growing demand for thermodynamically stable and highly polarizable materials with excess electrons in the fields of optics. In this study, a new class of theoretically designed materials (AxY@C16Te8 (A = K, Na, Li, and x = 2, 3 4)) are explored for optoelectronic and nonlinear (NLO) applications via DFT calculations. Various superalaklis (AxY (Y = O, N, F and x = 2, 3, 4)) are doped on C16Te8 nano-surface. The outcomes of DFT revealed high thermodynamic stability of these complexes. Natural bond orbital (NBO) charge analysis illustrated that charge transfer occurred from superalkali toward Te-containing [8]circulene (C16Te8). HOMO−LUMO energy gap is reduced after doping. Moreover, (AxY@C16Te8 (A = K, Na, Li, x = 2, 3 4, and Y = O, N, F) complexes exhibit remarkably large nonlinear optical (NLO) response. The static first hyperpolarizability (βo) of these complexes ranges between 3.28 × 103 – 2.60 × 105 au. The NLO response of the designed complexes is further explored by computing second hyperpolarizability (γtot), frequency-dependent hyperpolarizability, and nonlinear refractive index.

The affinity of glycine to gold nanoparticles in aqueous environments is of importance in a wide range of applications including protein engineering and wet chemical synthesis. In an aqueous environment, glycine exists predominantly as a zwitterion, however, the adsorption of zwitterionic glycine on gold and its impact on the vibrational spectra has not been well studied. This work uses density functional theory to investigate the adsorption of neutral and zwitterionic glycine molecules on two-, four-, six- and 20-atom gold clusters. The neutral glycine molecule preferentially binds to gold via the amine group rather than via the carboxyl group, with interaction energies ranging from 21 down to ≈11 kcal mol−1 for two to 20 atom gold clusters, respectively. For the zwitterion in an implicit solvent medium, binding can only occur via the carboxyl group. The interaction energy ranges from 23 to 13 kcal mol−1 for two to 20-atom gold clusters, respectively. Bader charges analysis and charge difference density maps show that electronic charge is transferred to the gold cluster. Vibrational frequencies and IR intensities were calculated for neutral and zwitterionic glycine and for all binding configurations on the gold clusters. The IR spectra of both neutral and zwitterion glycine molecules show the sharpest peak for C–O stretching modes. This C–O stretching mode redshifts by around 100 cm−1 neutral glycine binds via carboxyl group. In the case of the zwitterion, the sharpest peak remains at the same position after adsorption. The size of the gold cluster has a negligible impact on the vibrational IR spectra for both neutral and zwitterion glycine molecules.

Upon the adsorption and sensing of C2H2 and C2H4, we purpose pristine WTe2 monolayer as a promising candidate and uncover the enhanced mechanism of Ni-doping towards such two gas species in this work, using the density functional theory (DFT) method. Results show that pristine WTe2 monolayer performs physisorption upon C2H2 and C2H4 molecules with adsorption energies of −0.57 and −0.63 eV, and the small changes in its bandgap indicate the unsuitability for gas sensing use. The Ni-doping is energy-favorable with formation energy of −0.15 eV by substituting a Te atom on the WTe2 surface, and C2H2 and C2H4 adsorptions are both determined as chemisorption with adsorption energies of −1.40 and −1.22 eV. The electron redistributions are dramatically promoted in the Ni-WTe2/gas systems, and the obvious decrease of bandgap in Ni-WTe2 monolayer after C2H2 and C2H4 adsorptions, about 25.6% and 12.6%, suggests the strong potential for its exploration as a resistance-type gas sensor with sensing response of −97.8% and −85.4%. The analysis of recovery property reveals the reusability of Ni-WTe2 monolayer after several seconds exposure under UV light at 398 K. These findings give a deep insight into the WTe2-based gas sensor upon the typical gases in the transformer oil.

A first-principles study is performed to explore the magnetic properties of the 3d transition metal (TM) atoms embedded in a new two-dimensional(2D) nonmagnetic carbon sheet. By the adsorption of 3d metal atoms (M = Sc-Ni) on the single vacancy (SV) site of 2D carbon material, the M@SV complexes are nonmagnetic for M = Ti, Co and Ni. Other metal atoms doping can induce different magnetism. The magnetic moment of Sc@SV system mainly comes from the π electrons of carbon atoms, and these electrons virtual hopping leads to the ferromagnetic coupling interaction with Sc atom. For M = V, Cr, Mn and Fe systems, the more net spin electrons go the separate nonbonding d orbitals, giving the different magnetic moments. Meanwhile, due to the Hund’s rule, the metal atoms and the surrounding carbon atoms have the anti-ferromagnetic coupling interaction. By the simple spd hybridization model, we explore the origin of the various magnetism, and provide some new magnetic single-atom materials for the future spintronics devices and spin-dependent catalysts.

In present work, machine learning models are trained for the prediction of energy levels. Two large databases are explored in the search of efficient building blocks. Three polymers are selected as standard. New building blocks are selected on the basis of similarity index. New polymers are designed by keep the synthetic aspects in mind. Their energy levels are predicted using machine learning. Few best polymers are selected for density functional theory-based analysis. Detailed electronic and graphic properties are calculated. This study is an attempt to highlight how data-driven strategies can help to find unique building blocks and designing new-polymers.

In this study first-principles calculations based on density functional theory (DFT) were performed to study the nature of the electronic and optical characteristics of the gases CO2, CO, H2S, SO, and SO2 adsorption on indium phosphate InP bilayer surface. Four initial adsorption sites were chosen to investigate the more effective and sensitive adsorption location for the adsorbed gases. Our findings indicate that the adsorption of CO2 gas exhibits a physical nature, in contrast to the chemical nature gases. Delocalized electrons are observed in the interlayer region in the ELF of CO2 on the InP bilayer. This result suggests the absence of a chemical bond between the CO2 gas molecule and the InP bilayer. According to an analysis, a gas molecule's adsorption might be influenced by InP bilayer's optical properties. Overall, the calculations demonstrate an excellent potential of InP bilayer to act as a gas sensor for studies gases.

Nowadays, as a practical approach to enhancing energy density of a metal ion battery, discovering efficient electrode materials is the foremost option. At the beginning and end of metal adsorption, BeP2 is inherently metallic and delivers favorable electrical conductivity. According to first-principles computations, BeP2 can be considered potentially suitable electrode materials for Mg-ion battery. Notably, fully magnesium phase Mg2BeP2 for BeP2 offers a great theoretical capacity (578.35 mAh g−1) accompanied by single layer of Mg ions, which outperforms numerous formerly reported two-dimensional options. In the interim, it has been discovered that diffusion barrier and open-circuit voltage of BeP2, subsequent to complete adsorption of metal ions, exhibited an unexpectedly diminished value of 0.21 V. Contemporary research findings can facilitate discovery of innovative electrode materials of BeP2 classification catering to needs of metal ion batteries. It can be concluded that BeP2-based composites are promising anchor materials for advanced Mg-ion batteries.

Glyphosate is the most used broad-spectrum agrochemical due to its non-selective action mechanism. However, there are concerns regarding being a threat to aquatic and terrestrial lifeforms and the environment. In this study, we conducted a systematic theoretical investigation of the effect of pH on the electronic structure, physicochemical, and spectroscopic properties (IR, Raman, UV–vis, ECD, EI-MS, and NMR) of glyphosate and its zwitterionic structures. The lipophilicity of the zwitterions was studied with ADMET and DFT, and a significant discrepancy between the models was observed. Theoretical EI-MS provided insights into the degradation pathways and possible intermediates. The effect of protonation and hydration on the magnetic properties was described based on an implicit-explicit strategy to compute NMR chemical shifts for the zwitterions, in which the solvent has a considerable effect on the chemical shifts. Overall, our findings suggest that spectroscopic properties can be used to describe glyphosate-based zwitterionic structures.

R601a/R245fa mixture is one kind of promising working fluid in ORC. In this study, the thermal decomposition mechanism of R601a/R245fa mixture was studied by reactive molecular dynamic simulation (ReaxFF-MD) and density function theory (DFT). In the R601a/R245fa mixed working fluid system, pyrolysis begins with the CC bond breaking of R601a, generating a large number of CH3 radicals, which further decompose to produce a certain amount of H radicals. Due to the presence of R245fa, the hydrogen extraction reactions between CH3, H radicals and R601a, which have low energy barriers were inhabited to a certain extent. The addition of R245fa reduces the generation of small molecule flammable gases such as H2 and CH4, however, it increases the risk of HF generation. When the molar ratio of R245fa exceeds 0.5, pyrolysis will cause more serious HF corrosion problems than pure R245fa.