Taking into account that Sulfur hexafluoride (SF6) gas leakage can result in environmental pollution, the insulating oil used in high-voltage equipment can decompose into various detectable dissolved gases, allowing for the monitoring of its operational status. In this study, we use a CoO-doped SnSe (SnSe-CoO) monolayer to achieve strong adsorption of SF6 gas, CO, and C2H2 gas, and highly sensitive monitoring of H2 and CH4. Thus, the SnSe-CoO monolayer can serve as an adsorbent for SF6 gas leakage and a material for monitoring insulating oil-dissolved gas. Furthermore, we also observed that the adsorption energy of each gas on the intrinsic material increases with the solvent dielectric constant, facilitating the control of gas adsorption. Our research provides a significant theoretical foundation for future adsorption and monitoring of insulating gases and insulating oil decomposition gases.

This article reports various cross sections of electron scattering from C5H10 isomers, viz. 1-pentene, 2-methyl-2-butene, cis-2-pentene, trans-2-pentene and 2-methyl-1-butene. These molecules are scarcely investigated in terms of such interactions, especially cis-2-pentene, trans-2-pentene and 2-methyl-1-butene molecules for which no previous cross section data is available. The results presented here are obtained by the quantum mechanical formalism using optical potential method, for a wide energy range from the ionization threshold of the target to 5000 eV. Geometrical screening correction is included in this calculation to account for the overlapping charge densities of different atoms present in a molecule. Most of the data presented here are reported for the first time. The effect of structural difference on cross section is investigated through isomeric effect.

A comprehensive study of the structural, optical, and electronic properties of RbPbX3 (where X is Cl or F) perovskite crystals is reported herein. The calculations of the different physical properties of these two distinguishable RbPbCl3 and RbPbF3 perovskite crystals have been carried within the framework of the Density Functional Theory (DFT) approach for the cubic temperature-dependent phase. The study is motivated by the exploration of innovative perovskites materials for solar cells application due to the marvelous augmentation in power conversion efficiency (PCE) obtained by perovskite crystals (≈ 25% up to date). The investigation were undertaken for determining the perceivable role of the X element in their band gap energy features as well as the band structure proprieties. The simulations were commenced by determining the optimal lattice constants and the lowest total energy of both perovskite crystals. The exploration of the electronic properties of RbPbCl3 and RbPbF3 perovskite crystals have been studied by estimating their variation upon employing spin–orbit-coupling (SOC) and without taking into consideration the SOC interaction by means of LDA-pz and GGA-PBE exchange potentials within the framework of projector augmented wave method (PAW) and the Perdew–Burke–Ernzerh of LDA and (PBE) variant of the generalized gradient approximation (GGA). The integrated suite quantum-ESPRESSO is used for materials modeling, structure calculations, and electronic properties of the studied RbPbCl3 and RbPbF3 perovskite crystals. The thermo_pw driver is employed for the determination of the elastic properties whereas the optical properties were elucidated by aid of Yambo code through solving the many-body perturbation theory (MBPT) approach as introduced in the open-source code. The optical band gap of cubic RbPbCl3 and RbPbCF3 within LDA and PBE, were observed at (2.18, 2.2) eV and (2.4, 2.5) eV respectively. Compared and contrasted with those revealed by the electronic band gap energy of the systems, these obtained values are very consistent with the experimental. The two maximum peaks for the absorption coefficients are found to be within the visible range rending the two perovskite crystals in promising candidate for solar cell applications. Despite some quantitative differences, the material’s enhancement potential is well demonstrated by the absorption coefficient spectrum, refractive index, and conductivity. The study holds promise for solar cell applications and may pave the way for consideration of the RbPbCl3 and RbPbF3 as well as their doped analogs for perovskites-based solar cells as the next generation in the photovoltaic industry.

We performed first principles calculations on the recently synthesized NaReN2. This compound is the main product of the reaction between Re and NaN3 in forming the super hard material ReN2. Theoretical calculations of sodium rhenium nitride, such as band structure and density of states (DOS) were performed. The partial density of states (PDOS) was also included to determine the contribution of individual atoms to the electronic states. The theoretical data reveal that the material possesses a rather narrow bandgap of 0.26 eV. Semi-conducting materials with such low bandgap values have interesting applications in various fields. The optical properties were also studied indicating possible application of NaReN2 in opto-electronic devices. Excitonic study reveals the weak excitonic behavior of this material. Thus, first principles calculations on this material provide necessary theoretical information on physicochemical properties of NaReN2.

The equilibrium geometries, electronic structures, reactivity, and stability of C/C2-doped Aln0,± (n = 2–7) clusters were investigated computationally at B3LYP-D4/def2-TZVPP and CCSD(T)/def2-TZVPP levels of theory. The lowest energy structures of AlnC1,20,± clusters were the carbon atoms inserted inside the aluminium clusters. The stability of the neutral and charged clusters were investigated under various reaction conditions, such as dissociation of the clusters via Al0,+,C0,-,C20,--elimination and electron elimination from neutral (ionization) and anionic species (electron detachment). The dominant dissociation reaction channels are the Al-elimination from the neutral and anionic clusters, Al+-elimination from cationic clusters, rather than the C/C2-elimintion reaction. On the other hand, C-elimination are were more favorable compared to C2-elimination due to the stronger CC and Al-C bonds. In addition, binding energy, second-order difference of energy, chemical hardness, and electron affinity parameters were used to determine the stability and reactivity. The results show the singlet cluster (Al2,4,6C1,2 and Al3,5,7C0-20,±) have the greater stability than the doublet clusters (Al3,5,7C0-2 and Al2,4,6C1,20,±) and triplet clusters (Al2,4,6). It has been demonstrated that anionic clusters are more stable than the neutral species, and cationic species are less stable than that of neutral species. The current study could be useful in understanding the stability and reactivity of metal clusters after carbon doping, which is important in combustion, material science, and the astrochemical community.

The aim of this work is to use spin polarized density functional theory (DFT) to explore how functionalizing the periphery of FePc with F atoms affects its adsorption properties on reactive metals, specifically Rh and Ru. The results show that the interaction between FePc and the substrates is of chemisorption nature, which leads to a reduction in symmetry of the original four-fold rotational symmetry of FePc to C2 or lower. The symmetry reduction has a mixed electronic and geometric character, caused by the breakup of degenerate dxzanddyz orbitals, as well as the incommensurability between molecule and surface symmetries. Introducing fluorine to FePc weakens the interaction between the Ru (Rh) substrates and the organic part of the molecule, resulting in a C2 rotational symmetry reduction. Furthermore, this functionalization enhances the charge transfer to the molecule, which could be of interest to electronic applications.

Four rosin derivatives containing amide, pyridine and dehydroabietyl sub-units were synthesized. Their selective and sensitive recognition of Cu2+ and Fe3+ ions were confirmed by UV–vis and fluorescence spectra. Their detection limits for Cu2+ and Fe3+ were lower than the maximum allowable levels of Cu2+ and Fe3+ in drinking water. They could displace ethidium bromide (EB) molecules inserted into CT DNA base pairs and induce fluorescence quenching of CT DNA-EB system in a static mode. The negative ΔG values proved that the binding processes of the compounds to CT DNA were spontaneous. The negative values of both ΔH and ΔS solidified that the hydrogen bonds or Van der Waals was the driving force for the interactions between the four compounds and CT DNA. Metal ion recognition and DNA interaction indicate that the number of pyridine rings and the flexibility of the compounds had influence on the strength of the above activities.

A new kind of two-dimensional semiconductor, MA2Z4, has shown exceptional electrical and mechanical properties, that make it suitable for use as a semiconductor device. In this paper, metallic Ti3C2T2 (T = O or OH) and semiconductor TiSi2N4 van der Waals heterostructures are constructed, and their interfacial characteristics are investigated under the effect of biaxial strain and external electric field. Due to the different terminations on Ti3C2 surfaces, Ti3C2O2/TiSi2N4 exhibits an n-type Schottky contact whose Schottky barrier is 0.718 eV, and Ti3C2(OH)2/TiSi2N4 exhibits an Ohmic contact. Furthermore, the Ti3C2O2/TiSi2N4 heterojunction can be changed from n-type Schottky contact to p-type Schottky contact by applying biaxial strain or external electric field, while the Ti3C2(OH)2/TiSi2N4 heterojunction keeps an Ohmic contact unchanged during the process. Our results demonstrate their potential as candidates for tunable nanoelectronic devices and field-effect transistors.

Calculations of the photoionization cross section of C60 including all valence and core subshells have been carried out for photon energies up to 1 keV using density functional theory (DFT) and time-dependent DFT (TDDFT) within the framework of a fully molecular model. The high-energy valence subshell cross sections behave rather differently than the results from model potentials where the cross section falls far too rapidly with energy. This unphysical behavior of the model calculations is traced to smearing out of the carbon nuclei in the model potentials which makes it difficult for momentum to be conserved at the higher energies. Comparison with 60 times carbon atomic cross section sheds light on similarities and differences. The high energy behavior of individual valence cross sections reflects the amount of C 2s/2p mixing in the molecular orbitals.

Methane production from hydrate reservoirs using combined CO2 and chemical inhibitor injection is a potential method for simultaneous methane recovery and CO2 sequestration. Molecular dynamics simulations have been performed to study the dissociation of CO2 hydrates in the presence and absence of the ionic liquid, viz., [BMIM][PF6], at 250, 255 and 260 K and pressures ranging from 20 to 60 bar. Effect of [BMIM][PF6] on hydrate thickness has been demonstrated to be not significant by hydrogen bonding and order parameter analyses. Local number density profiles of guest and host molecules show that in presence of this ionic liquid, deviation from hydrate-like behaviour is less than in its absence. This is due to preferential association of CO2 with [PF6]- anion. The asymmetry in the density profiles of CO2 and H2O brings out the role of filled and empty partial cages at the interfaces on hydrate dissociation in the presence of [BMIM][PF6].

Diabatic surfaces generated for the ground state 11Σ+(11A′) as well as for the first excited electronic state 21Σ+(21A′) have been quantified for the C3 collision with H+ system employing the MRCI/aug-cc-pVQZ method. These collisions are significant in understanding the mechanism of energy transfer in astrophysics and molecular physics. For studying the dynamics of the interaction between the charge transfer and inelastic processes, properties such as non-adiabatic coupling matrix elements, and mixing angle have been determined. The computed surface and their properties will be useful in studying charge partitioning between the inelastic and charge transfer channels by wave packet quantum dynamics.

In this study, we use first-principles computational methods to investigate the structural, thermo-elastic stability, electronic and thermoelectric properties of LiYN (Y = Mg and Ca) half Heusler. The obtained results show that the compounds are structurally stable in α-LiYN phase and exhibit semiconductor behavior with band gap values of 2.412 eV (3.883 eV) and 2.340 eV (3.980 eV) when employing GGA (HSE) approach, respectively. The findings of the temperature dependence of the elastic constants illustrate the mechanical stability at high temperatures of α-LiYN, and they have a high melting temperature of 2034 K and 1544 K for LiMgN and LiCaN, respectively, which makes them more important in high temperature applications. Based on the thermoelectric results, we can also conclude that these compounds are promising for thermoelectric devices at high temperatures.

Van der Waals Heterostructure (vdwH) has excellent properties due to its unique composition, which makes it leading the research craze. Based on the first principles, the geometric stability, electronic and optical properties of doped ZrS2/GaSe vdwH have been studied in detail. The results show that ZrS2/GaSe vdwH has a typical Type-II band arrangement with an indirect band gap of 0.763 eV. Doping decreases the band gap and increases the optical absorption coefficient. After the initial heterostructure is adjusted by the layer spacing or the external electric field and strain are applied, the band gap values of the heterostructure can be observed to change regularly. It is noteworthy that when positive and negative electric fields and biaxial strain are applied to the doped heterostructure, the transition from indirect to direct band gap and from Type-II to Type-I is observed. In addition, ZrS2/GaSe vdwH exhibited better optical absorption performance than monolayer in the UV region, and doping, strain and electric field all improved the optical absorption capacity of ZrS2/GaSe vdwH in the visible region.

The Wiener indices of zigzag single walled carbon nanotubes (SWCNT) designated as (h, 0) and respective nanotori are expressed analytically as well recursively. The bond dissociation energies per CC bond (BDEC-C) and Young’s modulus of such nanotubes with fixed r but varying h (>5) are found to bear excellent linear correlations with the logarithm of their Wiener indices. Young’s moduli data for nanotubes (h, 0) with varying both h and r do not correlate linearly with the logarithm of Weiner indices but fit well with the sigmoidal (Boltzmann) curve.

The A15 structure of W, the β–W, exhibits better properties for spintronics applications than bcc α–W. Previous works found that impurities could stabilize β–W. It is therefore important to identify the role and effects of impurities in the material. Hence, we performed DFT-based calculations and investigated the effects of interstitial impurities (12.50% and 1.56% atomic impurity concentrations of H, O, and He) on the structural and electronic properties of β–W. We also investigated α–W for comparison. We found that the binding energy of O is more favored in β–W than in α–W. However, the cohesive energy per atom of β–W is higher than α–W only when there is 12.50% atomic concentration of O in the system. This suggests that O has the tendency to induce α–W-to-β–W transition at this concentration of O. We found that the binding energies of H in β–W are energetically more favorable than in α–W, but the cohesive energies per atom are higher in α–W. These results imply that it will require a larger amount of energy to form β–W with H as an impurity. We found no stable site for He. Interaction between impurities and W atoms induces structural changes and an increase in the electron density of states at the Fermi level which highlights the effects of impurities in β–W.

Ice is ubiquitous, and it has the unique characteristic of exhibiting many polymorphs. Although the rich polymorphism of water ice is due to the existence of hydrogen-order–disorder phases, the order–disorder transition of ice Ic remains unresolved. Through cryogenic transmission electron microscopy, we observed annealing process of ∼50-nm sized ice Ic islands on an amorphous SiN substrate at 100–130 K. Water molecules diffused freely on the surface of ice Ic and amorphous SiN under this condition, resulting the coarsening of islands. We found that ∼10 nm thick hydrogen-ordered cubic ices grew on the surface of ice Ic islands during coarsening. There might be hydrogen-ordered cubic ices on the surface of ice Ic in various objects in space.

Recently, temporary anion states of fluorine substituted benzenes have been probed via photodetachment experiments on oxygen-fluorobenzene anion complexes [O2⋅C6H6−nFn]−, n=0…6. Here, we complement these experiments with a computational characterization. For the ground electronic states, two isomers are identified: The first isomer class shows non-conventional hydrogen bonds, while the second shows carbon-oxygen contacts. For both isomer classes, the electron affinity of the complex is significantly higher than that of either moiety, and the electron affinity increase upon complex formation is studied in detail. Both isomer classes show strong O2−−C6H6−nFn interactions, and the extent of charge donation from O2− to the organic moiety is characterized. Moreover, we characterize charge-transfer excited states of [O2⋅C6H6−nFn]− anion complexes corresponding to neutral O2 bound to C6H6−nFn−. The charge transfer complexes form doublets and quartets, and here we focus on the minimal energy structure of the quartet state and characterize the doublet at the same geometry.

The fabrication of bi-component and three-component supramolecular networks based on hydrogen bonds was investigated by scanning tunnelling microscope (STM). Induced by successively introduced coronene (COR) and 1,3,5-benzenetricarboxylic acid (TMA), the intermolecular interactions between [1,1’-biphenyl]-3,4’,5-tricarboxylicacid (BPTC) were changed, leading to the structural transformation of the lamellar self-assembled nanostructure of BPTC on highly oriented pyrolytic graphite (HOPG). Eventually, the flower-like nanostructure of BPTC/COR and kagomé nanostructure of BPTC/TMA/COR were obtained on HOPG substrates respectively. This investigation of the multicomponent host-guest network could be useful for the construction of novel heterogenous molecular structures.

Molybdenum ditelluride (MoTe2) is a promising two-dimensional material with ultimate prospective usage in high performance photodetection devices. In this study, we elucidate how this may be revealed and discuss how structural and optoelectronic properties of MoTe2 can be numerically accurately simulated since earlier experimental and theoretical studies on the bandgap of MoTe2 produced contradictory findings. In doing so, GW-based functionals using Hubbard U and V corrections are included in density functional theory (DFT) calculations to improve bandgap estimations. Interestingly, we reliably demonstrated that the estimated values of the bandgaps of 0.83 eV and 0.73 eV obtained, respectively, within this framework of DFT+U+V and GW, perfectly match the reported experimental results. Specifically, the quantum espresso simulation package is used for accurate DFT calculations allowing thereby a comprehensive investigation of the impact of the Hubbard U correction on the bandgap of MoTe2. Additionally, the optical absorption spectrum is examined for both GW and RPA levels of theory using the Yambo simulation tool, allowing for a readily distinctly identification of the material’s light absorption spectrum. Contrasted by previous theoretical results, the random phase approximation (RPA) approach, which performs quite well in showing increased optical efficiency, reveals its effectiveness for obtaining appreciable gains in the values of the real, imaginary, refractive index, and extinction coefficient. The expected trends obtained with GW-based functionals using Hubbard U and V corrections approximate methods are encouraging, and altogether support ongoing attempts to optimize the physical properties of MoTe2 for high-performance photodetection systems by offering more precise bandgap predictions and valuable insights related particularly to the optical properties.

Carbon monoxide (CO) is an odorless, colorless and highly toxic gas, developing gas sensor with high sesitivity toward CO gas is critical for controlling combustion processes. In this paper, the characteristics of adsorption of CO, H2O, CH4, H2S, H2 and NH3 gases on Cu-doped MnO3 are investigated by first-principles calculations. The adsorption of CO on Cu-MoO3 shows the highest adsorption energy together with the largest differential charge density, indicating a strong interaction between CO and Cu-MoO3. The strong interaction is also demonstrated by the smallest adsorption distance of 1.526 Å between Cu-MoO3 and CO molecules. Moreover, the DOS of the system with the incorporation of CO moves to the lower energy levels and the DOS near the Fermi energy level increases, which will lead to significant change in conductivity of Cu-MoO3. It can be inferred that Cu-MoO3 show high sensitivity and selectivity toward CO gas.