Mulliken Population Analysis Research Articles

A first-principles study of the electronic, vibrational, and optical properties of planar SiC quantum dots

With the reported synthesis of a fully planar 2D silicon carbide (SiC) allotrope, the possibilities of its technological applications are enormous. Recently, several authors have computationally studied the structures and electronic properties of a variety of novel infinite periodic SiC monolayers, in addition to the honeycomb one. In this work, we perform a systematic first-principles investigation of the geometry, electronic structure, vibrational, and optical absorption spectra of several finite, but, fully planar structures of SiC, i.e. 0D quantum dots (QDs). The sizes of the studied structures are in the 1.20–2.28 nm range, with their computed HOMO(H)-LUMO(L) gaps ranging from 0.66 eV to 4.09 eV, i.e. from the IR to the UV region of the spectrum. The H-L gaps in the SiC QDs are larger as compared to the band gaps of the corresponding monolayers, confirming the quantum confinement effects. In spite of covalent bonding in the QDs, Mulliken charge analysis reveals that Si atoms exhibit positive charges, whereas the C atoms acquire negative charges, due to the different electron affinities of the two atoms. Furthermore, a strong structure property relationship is observed with fingerprints both in the vibrational and optical spectra. The wide range of H-L gaps in different SiC QDs makes them well-suited for applications in fields such as photocatalysis, light-emitting diodes, and solar cells.

Effect of Co-Doping on the Photoelectric Properties of the Novel Two-Dimensional Material Borophene

Borophene is a novel two-dimensional material with abundant crystal structure and photoelectric properties. We focus on the effect of co-doping on the electronic structure and optical properties of borophene using the first-principles method. The results show that the structure of Al and Ga co-doped borophene is obviously distorted because Al and Ga atoms have formed bonds with a bond length of 2.378 Å, and the two B atoms that bond together with Al and Ga are no longer formed bonds. However, it is also a two-dimensional planar structure after co-doping. After co-doping, the band gap width of the borophene system is narrowed from 1.409 eV to 1.376 eV, and the band gap is narrowed by 0.033 eV. Mulliken population analysis shows an obvious charge transfer between Al-B and Ga-B atoms in the co-doped borophene. The calculation of optical properties shows that the static dielectric constant ε1 (0) increases from 5.08 to 7.01, and ε2 (ω) is larger than that of the undoped sample in the low-energy range. Thus, the co-doping of Al and Ga can enhance the electromagnetic energy storage capacity and the visible light absorption ability. Although the reflectance of borophene is reduced by co-doping (the peak of the reflectivity can be decreased from 71% to 61% at E = 2.94 eV), it still presents metallic reflection characteristics. The static refractive index n0 can be increased from 2.25 to 2.65 by co-doping. The extinction coefficient shows strong band edge absorption at the low-energy range with an absorption edge of 0.85 eV. The light loss is limited to a very narrow energy range of approximately 7.30 eV, which indicates that borophene co-doped with Al and Ga can also be used as a light storage material. The optical conductivity reaches its maximum at E = 1.78 eV and 2.52 eV, which correspond to the light irradiation with a wavelength of 698 nm (red light) and 492 nm (cyan light), respectively. The results show that the Al-Ga co-doped borophene is sensitive to cyan light and red light, so it can be used to make photosensitive devices. The results can hopefully fill the gap in the application of borophene in semiconductor photoelectric devices and provide a theoretical basis for its application.

The impact of lead on structural, electronic, and vibrational properties of pristine C36 and its boron, nitrogen-dopant C36 on pentagonal and hexagonal rings

In this work, lead's impacts on the structural, electronic, and vibrational characteristics of pure C36 and C36 doped with boron and nitrogen on pentagonal and hexagonal rings are calculated using the DFT method. We provide an in-depth examination of these characteristics and how lead affects them. The adsorption energy, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), and electrostatic potentials at the isosurface (EPI) have been studied in detail. Assess the ring dependence of the lead adsorption energy for the hexagonal and pentagonal rings of pristine C36 and B and N impurities at the substitutional site. The adsorption energy for the Pb on pristine C36 is endothermic; however, it is exothermic for the Pb on NB-doped C36 but has different values on the pentagonal and hexagonal rings. The results demonstrate that nitrogen and boron doping significantly increased the Pb atom's adsorption energy when the dopants occupied pentagonal sites. In addition, the bond lengths surrounding the impurity and the bond lengths of Pb atoms placed on pristine C36, BN-doped hexagonal ring, and BN-doped pentagonal ring in C36 are investigated. The electrostatic potential isosurface (EPI) surrounding the BN-doped hexagonal and pentagonal rings of C36 is described. The Mulliken charge transfer analysis demonstrates that the interaction between NB-doped C36 fullerene and lead (Pb) has a substantial effect on the charge transfer process and the reactivity of the doped system towards lead. However, the quantity of charge transmitted depends on the impurity's location on the hexagonal and pentagonal rings. These findings aid in the atomistic understanding of the interaction between a single Pb atom on the surface of C36 and BN-doped C36 at various rings. Our findings not only shed light on the complex interplay between lead and C36 but also offer valuable insights into potential applications in materials engineering and environmental remediation.

Spectroscopic (FT-IR, FT-Raman, UV–Vis and NMR) and computational (DFT, MESP, NBO, NCI, LOL, ELF, RDG and QTAIM) profiling of 5‑chloro-2‑hydroxy-3-methoxybenzaldehyde: A promising antitumor agent

In this study, the benzaldehyde derivative 5-chloro-2-hydroxy-3-methoxybenzaldehyde (5C2H3MB) was characterized using spectroscopic techniques. Geometric parameters and complete fundamental vibrational assignments were simulated using DFT/B3LYP/6-311++G(d,p). The 1H and 13C chemical shifts, computed using the GIAO method, were in agreement with the experimental findings. The electronic properties of 5C2H3MB were analyzed using time-dependent density functional theory (TD-DFT) to determine various electronic parameters, including HOMO-LUMO energies. NBO analysis was performed to determine the numerous hyper-conjugative interactions responsible for the stability of the compound. In addition, Mulliken population analysis and Molecular Electrostatic Potential Surfaces (MESP) analysis were conducted to identify electron-rich, electron-poor, reactive sites, and bonding characteristics of the titled compound. The topological analyses ELF, LOL, NCI, QTAIM, and RDG were performed using Multiwfn software, and global reactivity parameters and Fukui functions were also predicted. Molecular docking studies were conducted to confirm the biological activity by simulating the binding orientation and affinity of 5C2H3MB against transferase inhibitor and human phosphorylated IRE1 alpha, showing a binding energy of −5.1, −5.3 and −5.9 kcal/mol, indicating its potential as an antagonist.

Theoretical and computational study of benzenium and toluenium isomers.

Four methods of computational quantum chemistry are used in a study of hyperconjugation in protonated aromatic molecules. Benzene, benzenium, toluene, and four isomeric forms of toluenium are examined using the self-consistent field level of theory followed by configuration interaction and coupled cluster calculations, as well as density functional theory. Results for proton affinities, geometric parameters, atomic populations, dipole moments, and polarizabilities are reported. The calculated results are in good agreement with previous computational studies and with experimental data. The presence of hyperconjugation is evident from the shortened carbon-carbon bond lengths in the aromatic ring and concomitant changes in dipole moments and polarizabilities. The proton affinities of benzene and toluene compare well with experimental values. The examination of all of the toluenium isomers reveals that the position of the methyl group has a minor impact on the strength of hyperconjugation, although the most stable isomer is found to be the para form. Mulliken population analyses indicate that the addition of a proton contributes to aromatic hyperconjugation and increases the strength of π-bonds at the expense of σ-bonds.

Lead-free novel perovskite Ba3AsI3: First-principles insights into its electrical, optical, and mechanical properties

Lead-free halide perovskites are a crucial family of materials in the fabrication of solar cells. At present, Solar cells are facing several challenges such as mechanical and thermodynamic instability, toxicity, unsuitable optical parameters, bandgap, and absorption coefficient. Ba3AsI3 is a halide perovskite which has demonstrated good efficiency and tremendous promise for usage in solar cell applications, and it offers a possible solution to these issues. In this study, the properties of the Ba3AsI3 perovskite solar cell were investigated using first-principles density functional theory (FP-DFT) calculations with the CASTEP (Cambridge serial total energy package) formulation. Most of its physical qualities, including its elasticity, electrical composition, bonding, optoelectronic characteristics, and optical characteristics have not yet been explored. In this work, these unexplored properties have been thoroughly investigated using density functional theory-based computations. The Born-Huang criterion and phonon dispersion characteristics have revealed that the material is mechanically stable. The bonding nature has been investigated using the density of states curves, Mulliken population analysis, and electronic charge density. Additionally, different elastic parameters demonstrate that Ba3AsI3 has reasonably high machinability and is mechanically isotropic. ELATE's three-dimensional visualization and optical properties also show isotropic behavior in all directions. The band structure shows that the bandgap is direct. Based on its direct bandgap, stability, large range of absorption coefficient, and suitable optical parameters, Ba3AsI3 is recommended as an absorber layer for solar cell fabrication in a near future.

First-principles study of V3+ adsorption on MXene toward vanadium redox flow battery

The sluggish kinetic of V2+/V3+ redox reaction limits the performance of vanadium redox flow battery (VRFB). As one of the critical steps of negative reaction, the adsorption process of V3+ on catalyst plays a significant role. Owing to the high conductivity and catalytic activity of MXene materials, the adsorption behavior of V3+ on MXenes (Ti3C2O2, Nb3C2O2, Sc3C2O2) and MXenes with oxygen vacancy (Vo-Ti3C2O2, Vo-Nb3C2O2, Vo-Sc3C2O2) were revealed through first-principles based on density functional theory (DFT). Band structure, adsorption energy, Mulliken charge population, density of state, partial density of states and charge density difference were calculated. The results show that the adsorption mechanism of V3+ on MXenes is chemisorption and oxygen vacancy efficiently promotes the adsorption energy for V3+. The strong interaction between V3+ and MXenes is ascribed to orbital hybridization and overlapping. The adsorption energy of V3+ on Sc3C2O2 with oxygen vacancy (Vo-Sc3C2O2) reaches −98.255 kcal/mol. Meanwhile, the most obvious electron transfer phenomenon exists on the surface of Vo-Sc3C2O2. Vo-Sc3C2O2 shows the strongest metallicity and the largest adsorption energy for V3+, which presents potential candidate as catalyst for V2+/V3+ redox reaction.

One-dimensional polymer of copper with salicylic acid and pyridine linkers: Synthesis, characterizations, solid state assembly investigation by hirshfeld surface analysis, and computational studies

A new one-dimensional polymeric copper complex [Cu(DNSA)py] with salicylic acid and pyridine was synthesized and characterized by many techniques, including FT-IR, UV–Visible, elemental, TGA/DSC, and single crystal XRD analysis. In the crystal structure, two 3,5-dinitrosalicylic ligands were chelated by the copper cation, in which one ligand was coordinated by the carbonyl O-atom and one of the carboxylate O-atoms, while another symmetry-related ligand was coordinated by the O-atoms of the carboxylate group to form distorted square pyramidal geometry. Thus, a one-dimensional polymer structure is formed, extending along the b-axis. The solid-state assembly was stabilized by various intermolecular interactions, as examined through Hirshfeld surface analysis. Voids analysis was carried out to predict the response of the crystal under external pressure. The most stable structure of the [Cu(DNSA)py] monomer resulted from density functional theory (DFT) using the B3LYP/def2-TZVPP. The 6–311G(d,p) level of theory demonstrated that the Cu atom adapts distorted square pyramidal geometry. The MEP surface and Mulliken charge distribution identified the Cu monomer atoms suitable for electrophilic and nucleophilic attacks. Frontier molecular orbital (FMO) analyses were conducted to anticipate the stability and chemical reactivity of the [Cu(DNSA)py] monomer and its ligand (DNSA). Furthermore, the quantum chemical descriptors of the title compound were obtained from EHOMO and ELUMO energy values.

Multi-Spectroscopic and TD-DFT Studies on Chromogenic and Fluorogenic Detection of Cyanide in an Aqueous Solution.

Different spectroscopic techniques and Density Functional Theory (DFT)/Time-Dependent Density Functional Theory (TDDFT) calculations have been employed to investigate the dual channel CN- detection behaviour of the developed chemo-dosimeter (AK3). The CN- with AK3 reaction triggered a colour change from pale yellow to colourless and enhanced fluorescence. UV-Vis, fluorescence, 1H & 13C NMR and mass techniques coupled with theoretical calculations (Mulliken charges, dihedral angles) revealed that the CN- sensing process mechanism involves deprotonation of the N-H group followed by nucleophilic addition reaction. Detailed TD-DFT calculations showed that the relaxation of excited electrons from LUMO and to two different ground states is responsible for the weak/moderate fluorescence of AK3. Nucleophilic addition of CN- to the C-atom of the CH = CH bridge terminated the π-conjugation between donor and acceptor regions, reduced the coplanarity, decreased the ICT transition and consequently enhanced the fluorescence of the probe. The practical utility of the probe was demonstrated by detecting cyanide in food materials and determining CN- in environmental water samples.

Investigating the effect of electrostatic field on electronic structures of C58N2 molecules from SCC-DFTB simulations

Self-consistent charge density functional tight-binding simulations are performed to investigate the effect of externally electrostatic field on nitrogen-doped fullerene C58N2 molecules. Based on the obtained geometric structures of twenty-three C58N2 configurations, electric field is applied to six selected configurations. We analyze the effects of the direction and strength of the electric field on the HOMO and LUMO energy levels, chemical potential, energy gap, dipole moment, Mulliken populations on atoms, and the variations of molecular orbitals at HOMO and LUMO energy levels of these configurations. The calculation results show that the electric field can change them. The effects of the electric field on the Mulliken charge distribution on the atoms in each configuration present complex patterns, and changing electric field’s direction and strength significantly affect the molecular orbitals. Here, variation of electric field direction can change the phase of molecular orbitals of the configuration having relatively high energy, and the change in the strength of the electric field has a more pronounced effect on the electron distribution at the LUMO levels.

A combined first-principles calculations and X-ray photoelectron spectroscopy of Ce2T3X9 (T = Rh, Ru, Ir; X = Al, Ga): Possible strong topological insulator state in Ce2Ir3Al9

We calculated electronic structure of Ce2Rh3Ga9, Ce2Ru3Ga9, La2Ir3Al9 and Ce2Ir3Al9 compounds and we found that Ce2Ir3Al9 may exhibit strong topological insulator state according to Z2 index estimation based on parity algorithm and shape of band structure near Fermi level. The same algorithm shows strong topological insulator state for La2Ir3Al9 and Ce2Rh3Ga9 compounds, but their band structure near Fermi level is more like semimetallic one. Ce2Ru3Ga9 is a normal metal. Our calculations show no magnetic ordering for studied compounds. We also measured the XPS (X-ray Photoelectron Spectroscopy) spectra for these materials, and compared the valence band with simulated spectra, where good agreement was found. Core level states were also investigated and compared with Mulliken population analysis results. According to our measurements and calculations, the highest Ce valence is observed for Ce2Ir3Al9 whereas for Ce2Rh3Ga9 and Ce2Ru3Ga9 the Ce valence is smaller. Hybridization between conduction electrons and 4f states is very small, and for Ce2Ru3Ga9 essentially negligible.

Two-Dimensional Artificial Ge Superlattice Confining in Electronic Kagome Lattice Potential Valleys.

Constructing two-dimensional (2D) artificial superlattices based on single-atom and few-atom nanoclusters is of great interest for exploring exotic physics. Here we report the realization of two types of artificial germanium (Ge) superlattice self-confined by a R25.3° superstructure of bismuth (Bi) induced electronic kagome lattice potential valleys. Scanning tunneling microscopy measurements demonstrate that Ge atoms prefer to be confined in the center of the Bi electronic kagome lattice, forming a single-atom superlattice at 120 K. In contrast, room temperature grown Ge atoms and clusters are confined in the sharing triangle corner and the center, respectively, of the kagome lattice potential valleys, forming an artificial honeycomb superlattice. First-principle calculations and Mulliken population analysis corroborate that our reported atomically thin Bi superstructure on Au(111) has a kagome surface potential valley with the center of the inner Bi hexagon and the space between the outer Bi hexagons being energetically favorable for trapping Ge atoms.

Comparative study of cationic Nile blue and anionic methyl orange dyes adsorption in water on the (110) surface of metal chlorides by DFT and MD approaches

Computational studies using density functional theory (DFT) and molecular dynamics simulations (MD) provide a valuable way to evaluate the removal of dyes by different adsorbents. In this study, Nile blue (with a positive charge; NB+) and methyl orange (with a negative charge; MO−) were used to examine the adsorptive performance of metal chlorides MCl2 (where M = Mg, Mn, Zn or Ni) from water. The calculated gap energies of NB+ and MO− were 5.333 and 2.395 eV, respectively, suggesting that the NB+ molecule is more reactive, electrophilic and can adsorb strongly on the MCl2 surface compared to MO−. Frontier molecular orbitals, Mulliken charge and an electrostatic potential map were used to explain the redox reactive sites of the investigated molecules. In addition, possible donor–acceptor interactions of molecules were assessed by natural bond orbital analysis. The negative values of back-donation energy ΔEback-donation for both dyes reflected that back donation for both dyes was energetically favorable. Furthermore, the most stable energy configuration of NB+ and MO− adsorption on MCl2 was determined by MD simulations. These simulations showed that both dyes can be adsorbed onto the MCl2 (110) surface in a nearby horizontal position. The radial distribution function peak values for all systems occurred at distances greater than 3.5 Å, indicating that the dyes were physically adsorbed onto the MCl2 surfaces through van der Waals interactions. The negative values of adsorption energy for both studied dyes indicated spontaneity of the adsorption process. Furthermore, MD simulations revealed that the adsorption energies between NB+ and MCl2 were much higher than between MO− and MCl2.

Investigation on 5-Isopropyl-2-Methylphenol via Quantum Chemicals, Pharmacokinetics, Molecular Docking and Cytotoxicity Evaluation Against Breast Cancer

The 5-isopropyl-2-methylphenol (5IP2MP) molecule, a monoterpenoid phenol mostly existing in the essential oil of Origanum vulgare L., was used as a potent breast cancer inhibitor in this present investigation. First, the structural and spectroscopic properties of the 5-isopropyl-2-methylphenol (5IP2MP) molecule were assessed via density functional theory (DFT) calculation. The structural optimization was performed through the DFT/B3LYP method with the 6-311++G (d,p) basis set, and the structural geometry was calculated. From the optimized structure of 5-isopropyl-2-methylphenol, vibrational frequencies were allotted and related with analytically calculated vibrational frequencies, the UV–Visible spectrum was theoretically simulated, and absorbance was experimentally confirmed. The 5-isopropyl-2-methylphenol’s reactive potential was further investigated through a molecular electrostatic potential surface. Exploiting the HOMO-LUMO energies and energy gap, the molecular reactivity and stability of the 5-isopropyl-2-methylphenol molecule were assessed. Mulliken and natural population analysis revealed the charge distribution over the atoms of 5-isopropyl-2-methylphenol. The bioactivity of the 5IP2MP was confirmed through natural bond orbital analysis. Thermodynamic evaluation has been utilized to acquire values of 5-isopropyl-2-methylphenol’s thermodynamic parameters that reveals the thermal stability of the title molecule. To determine the bonding domains and weakest interactions in 5IP2MP, topological investigations have been carried out based on electron localization function, localized orbital locator and reduced density gradient. Through the DPPH assay, the antioxidant potential was confirmed. The physicochemical and pharmacokinetic studies confirm the drug-likeness properties of 5-isopropyl-2-methylphenol. The anti-cancer potential of 5-isopropyl-2-methylphenol in contradiction to breast cancer proteins was confirmed through molecular docking analysis, which showed the highest binding affinity was detected against NAMPT with –7.9 kcal/mol. The previously chosen title chemical might be promoted as a possible pharmacological candidate for the development of new breast cancer prevention medications. The in vitro cytotoxicity studies exhibited the IC50 value of 67.96 [Formula: see text]g/ml with T-47D cells for a time period of 24 h. Overall, this study showed that the 5IP2MP molecule possesses better structural stability, reactivity and excellent anticancer activity in both in silico and in vitro studies.

Synthesis, crystal structure, DFT, Hirshfeld surface, 3D energy frameworks analysis and molecular docking of pyrimidine derivative: A theoretical and experimental approach

Using X-ray diffraction, FT-IR, 1H, 13C NMR, and UV–Vis spectra as well as theoretical DFT calculations, Ethyl-2-methyl-4-phenyl-3,4-dihydro-2H-benzo[4,5]thiazolo-[3,2-a]pyrimidine-3-carboxylate (T[3,2-a]P) has been synthesized and characterized. Physicochemical characteristics have been compared to examine stability. The most stable optimized structure was identified using the B3LYP/6–311++G(d,p) basis set, followed by UV–Vis and NMR analysis. TD-DFT analysis gave more information on how to estimate the electronic transitions in the UV–Vis spectra. In addition to the energy framework calculations, the Hirshfeld surface analyses have been demonstrated and discussed. The calculated band-gap energy of the pyrimidine derivative for various solvents and the estimated maximum wavelength (λ) absorbance were compared to the outcome of experiments. There were additional studies regarding the MEP map, surface area maps, and chemical reactivity. Additionally, topological and Mulliken charge distribution investigations were included. A pyrimidine derivative may be used as a chemotherapeutic and anticancer drug, according to docking experiments that were used to examine the interactions of the ligand (T[3,2-a]P]) with certain protein targets. The current study may lead to the identification of pyrimidine derivative as a possible therapeutic molecule. The practical and theoretical results were remarkably similar in terms of geometric and spectroscopic characteristics.

Synthesis, DFT, in silico anticancer, ADME and toxicity prediction study of (E)-2-(2-(3,4-dihydronaphthalen-1(2H)- ylidene)hydrazineyl)-4-(4-methoxyphenyl)thiazole

In the current paper, we describe computational molecular modeling to investigate the quantum chemical, spectroscopic, MESP and in-silico Anticancer, ADME and toxicity study of (E)-2-(2-(3,4-dihydronaphthalen-1(2H)-ylidene)hydrazineyl)-4-(4-methoxyphenyl)thiazole by one pot three component reaction. DFT method with B3LYP/6-311G(d,p) level was used to optimize the geometry, molecular electrostatic potential (MESP), Mulliken charges and vibrational assignments. The UV-Vis assignments, frontier molecular orbital (FMO), electronic parameters, and global descriptor were studied using the TD-DFT method with CAM-B3LYP/6-311G(d,p) level. In-silico anticancer study revealed favorable binding interaction with an excellent docking score comparable to the anticancer drug Dasatinib. The molecular docking study found that, target 4xt2 receptor’s amino acid residues VAL422B, LEU407D, MET426D, TYR327A, GLN421B, SER424B, and LEU423D play a vital role. The title compound has the requisite toxicity and ADME profiles, and it has the potential to be therapeutic.

Structural, electronic, and thermoelectric properties of hydroxyl groups adsorption on SnO2 (110) surface: A first‐principles study

Structural, electronic, and thermoelectric properties of bridging OHb and terminal OHt groups adsorbed on stoichiometric SnO2 (110) surfaces have been investigated using density functional theory and semiclassical Boltzmann transport theory with effective core pseudopotential implemented in CRYSTAL17 program. Our results indicate that H and OH yield significant structural relaxation around the adsorption sites O2c and Sn5c. The results have shown that the absolute value of adsorption energy increases with decreasing the coverage from 1 to 1/4 monolayer. Mulliken charge analysis, band structures, and density of states were calculated and discussed. We found that H and OH adsorption increases the band gap energy from 2.81 eV for clean surfaces to 3.04, 2.95, and 2.89 eV with, respectively, 1, 1/2 and 1/4 monolayer surface coverages. Thermoelectric properties revealed that the presence of hydroxyl groups on the SnO2 (110) surfaces may enhance the Seebeck coefficient, electrical conductivity, and electronic thermal conductivity.

Exploring electronic properties of zinc oxide using pure and hybrid density functional theory and Compton profiles

To check the viability and applicability of available experimental Compton profiles (CPs) of ZnO, we have computed Mulliken population (MP) and CPs using pure and hybrid density functional theory (DFT) within the basis of linear combination of atomic orbitals (LCAO) scheme. Pure DFT have been employed within local density approximation, generalized gradient approximation (GGA) and second order GGA (SOGGA) whereas for hybrid exchange and correlation energies the standard WC1LYP and B1WC hybrid schemes are adopted. A quantitative comparison of theoretical and the available experimental CPs unambiguously identify WC1LYP as a better choice for reproducing experimental momentum densities, and thereafter hybrid approach for generating accurate Eigen functions of ZnO. Further, MP analysis reports the dominancy of ionic character in the compounds. We have also scaled the CPs of ZnO and CdO using WC1LYP for equal-valence-electron-densities and concluded about more ionic character in ZnO than that in CdO.

Theoretical research the mechanism on the Ir/Ni (111) catalyst surface for CO2 methanation reaction

Iridium (Ir) demonstrates exceptional properties in CO2 hydrogenation reactions, yet the reaction mechanism remains unclear. Utilizing Density Functional Theory (DFT) calculations, the reaction mechanism on the Ir/Ni (111) surface has been investigated. Mulliken charge analysis indicates that CO2 is securely adsorbed and activated on the Ir/Ni (111) surface, forming CO2*, which is crucial for the subsequent hydrogenation process. By evaluating both the reaction energy barrier and the heat of reaction, the optimal methanation pathway CO2*→ COOH*→ CO*→ HCO*→ HCOH*→ CH*→ CH2*→ CH3*→ CH4* has been identified. The step of hydrogenation leading to HCO* is recognized as the rate-determining step in methanation, displaying the highest reaction activation energy. Furthermore, a greater energy barrier for C* formation proves advantageous in enhancing anti-carbon deposition properties and prolonging catalyst lifespan. Concurrently, the capability for C* hydrogenation sees dynamic and thermodynamic improvements, potentially augmenting the catalyst's methanation performance.

A Theoretical Study on the Unique Site Preference and Atomic Ordering of Hexagonal CoSn‐type Ternary Intermetallic Compound Co3Ge2Sn

AbstractThe inclusion of Ge in hexagonal B35 type CoSn leads to the formation of a new ternary substituted ordered variant Co3Ge2Sn. The experimentally reported crystallographic site‐occupancy pattern of this compound has been fundamentally addressed by the PBE‐GGA density functional theory‐based Mulliken population analysis. The site preference of Ge in the structure of Co3Ge2Sn is governed by the rule of ‘topological charge stabilization’. It turns out that the covalent inter‐layer heteroatomic Co−Ge bonds play a profound impact on the formation and stability of the compound. The structure of Co3Ge2Sn is decided by a combined factor of site energy and bond energy.