Density Functional Theory Perspective Research Articles

Influence of pyrite surface defects on xanthate adsorption: A density functional theory perspective

Many scholars have studied the adsorption behavior of various ions and agent molecules on pyrite surfaces based on density functional theory (DFT) calculations, however, the adsorption behavior of pyrite by surface defects has been relatively less studied. In this study, we try to produce defects on the surface of pyrite by hydration and study them systematically. The effects of pyrite surface defects on the molecular adsorption of xanthates were investigated on the atomic scale by combining DFT calculations, and AFM observation methods, respectively. The results indicate that oxygen molecules can indirectly participate in hydration reactions and promote crystal defect generation. In addition, the absence of coordination intensifies the electron transfer of pyrite, which favors the formation of new coordination with xanthates, and the adsorption energy is also reduced. Defects lead to an increase in the number of xanthate molecules at the adsorption site, and the adsorption capacity is also enhanced. The adsorption morphology was analyzed by AFM measurements to confirm the DFT calculation results. The complex interfacial system of sulfide ores was investigated, and it was found that the hydration process of sulfide ores generates surface defects, which further promote xanthate molecules adsorption. The results extend the traditional electrochemical adsorption theory of sulfide ores and provide theoretical support for the study of the molecular dynamics adsorption process on the surface of sulfide ores.

A DFT perspective on organometallic lanthanide chemistry.

Computational studies of the coordination chemistry and bonding of lanthanides have grown in recent decades as the need for understanding the distinct physical, optical, and magnetic properties of these compounds increased. Density functional theory (DFT) methods offer a favorable balance of computational cost and accuracy in lanthanide chemistry and have helped to advance the discovery of novel oxidation states and electronic configurations. This Frontier article examines the scope and limitations of DFT in interpreting structural and spectroscopic data of low-valent lanthanide complexes, elucidating periodic trends, and predicting their properties and reactivity, presented through selected examples.

Chemical properties of superatomic Li3O clusters from a density functional theory perspective: formation of chloride and adsorption behavior on graphynes.

Superatomic clusters have received a lot of attention due to their ability to mimic the electronic configurations of individual atoms. Despite numerous studies of these clusters, their ability to mimic the chemical properties of individual atoms is still unclear. This also applies for Li3O/Li3O+ clusters which simulate the Na atom and its ion, but their capabilities to form a salt or be adsorbed on surfaces remain unexplored. In this work, a density functional theory investigation was performed to study the chemical formation and adsorption behavior of the superatomic Li3O cluster. The results show that Li3O mimics the chemical properties of the sodium element to form Li3O chloride and be adsorbed on graphdiyne and γ-graphyne with similar binding energy as the sodium adsorbate cases. Beyond the isolated cluster individuals, superatoms are demonstrated as elements from the 3D periodic table to construct compounds and attach onto solid surfaces.

Complimentary Computational Cues for Water Electrocatalysis: A DFT and ML Perspective

AbstractHeterogenous electrocatalysis continues to witness propagating interest in a plethora of non‐limiting electrochemical fields. Of which, water electrolysis has moved from lab‐scale systems to commercial electrolyzers albeit high dependence on historic benchmark noble‐metal based catalysts is still the status quo. Notwithstanding, advances in material groups such as single‐atom catalysts, perovskites, high‐entropy alloys, among others continue to see an increased interest toward utilization in next‐generation electrolyzers. To that end, progress in electrocatalyst discovery techniques is revolutionized through synergistically combining density functional theory (DFT) and machine learning (ML) techniques. The success of ML herein depends on numerous interlinked factors such as the algorithm employed, data availability and accuracy, with descriptors being critical to encapsulate physicochemical perspectives. Historic utilization of ML frameworks in areas other than materials discovery has left a lack of standardization toward appropriating suitable methods of high‐throughput DFT, ML approaches, and feature engineering that bridge the gap between activity‐structure‐electronic relationships. This review outlines needed considerations toward DFT calculations, important criteria during filtering out screened surfaces, and synergistic approaches toward utilizing theoretical and/or experimental datasets for formulating effective ML frameworks. Persisting challenges, perspectives, and recommendations thereof are highlighted to expedite and generalize future work pertaining to high‐volume water electrocatalysis discovery.

Study of electronic and transport properties of some topological semimetals XPtBi(X=Gd,Nd,Y) compounds

We have reported the electronic and thermoelectric properties of rare-earth half-Heusler XPtBi(X = Gd,Nd,Y) topological semimetals(TSMs)compounds from the perspective of density functional theory. We have reported that the inclusion of spin orbit coupling (SOC) made more dense bands near fermi level which will be able to tune the electronic bands and well controlled twisting of the spin order which is mostly applicable to spintronic applications. Our results show that the band gap crossing is more near fermi level by the inclusion of SOC. We have reported that LSDA + U has strong effect on unfilled X-f states and hence shifts the bands towards Fermi level. We have found different topological states in these compounds in spin up and spin down states for GdPtBi, NdPtBi and YPtBi. We have further reported the transport properties of these TSMs with and without SOC in terms of figure of merit. Our results confirm that with the inclusion of SOCs in YPtBi power factor get enhanced appreciably for thermoelectric uses.

Outstanding NLO response of K3O@thia[n]circulenes; a DFT and molecular dynamics perspective

The nonlinear optical (NLO) response of superalkali (K3O) doped thia[7&8]circulenes (1–18) is analyzed through density functional theory (DFT) calculations. The high interaction energies illustrate thermodynamic feasibility of these complexes. Natural bond orbital (NBO) charge analysis confirmed that electronic charge is transferred from K3O toward thia[7&8]circulenes. Additionally, the lowest unoccupied molecular orbital (LUMO)—the highest occupied molecular orbital (HOMO) energy gaps are reduced up to 0.81 eV after doping. Polarizability (α o) and the first hyperpolarizability (β o) values are used to estimate NLO response of doped circulenes. The highest α o and β o obtained for K3O doped thia[7&8]circulene (9) are 7297 au and 3.03 × 108 au, respectively. Two level model illustrates that the excited dipole moment as decisive factor for enhancement of NLO response. The electronic excitation is confirmed from ultraviolet-visible (UV–vis) spectroscopic analysis where all doped circulenes showed bathochromic shift. Ab initio molecular dynamics depicts strong interaction and high thermal stability of K3O doped thia[7]circulene 9. Thus, K3O doping on thia[n]circulenes (n = 7&8) remarkably enhanced the NLO response which assures the use of respective complexes in designing of building blocks for future optics.

Structural and Biological Properties of 4-Dimethylamino Benzoic Acid: An Insight from the DFT Perspective

The structural investigation of 4-Dimethylamino benzoic acid using FT-IR, FT-Raman, UV, and NMR spectroscopic techniques was done systematically. The vibrational assignments, IR, and Raman scattering activity were computed by the density functional theory (DFT) using the 6-311++G(d,p) basis set and the B3LYP method. Experimental and theoretical parameters were compared. According to orbital natural bond calculations, the compound's stability is due to hyper-conjugative interactions and a hydrogen-bonding network. Molecular Electrostatic Potential (MEP) is also performed. HOMO and LUMO energies have been identified. The compound was docked with Adenovirus protein ID 3N0I, and the binding energy was found to be -4.4 kcal/mol.

Probing the Origins of Puzzling Reactivity in Fe/Mn-Oxo/Hydroxo Species toward C-H Bonds: A DFT and Ab Initio Perspective.

Activation of C-H bonds using an earth-abundant metal catalyst is one of the top challenges of chemistry, where high-valent Mn/Fe-oxo(hydroxo) biomimic species play an important role. There are several open questions related to the comparative oxidative abilities of these species, and a unifying concept that could accommodate various factors influencing reactivity is lacking. To shed light on these open questions, here, we have used a combination of density functional theory (DFT) (B3LYP-D3/def2-TZVP) and ab initio (CASSCF/NEVPT2) calculations to study a series of high-valent metal-oxo species [Mn+H3buea(O/OH)] (M = Mn and Fe, n = II to V; H3buea = tris[(N'-tert-butylureaylato)-N-ethylene)]aminato towards the activation of dihydroanthracene (DHA). The H-bonding network in the ligand architecture influences the ground state-excited state gap and brings several excited states of the same spin multiplicity closer in energy, which triggers reactivity via one of those excited states, reducing the kinetic barriers for the C-H bond activation and rationalizing several puzzling reactivity trends observed in various high-valent Mn/Fe-oxo(hydroxo) species.

Surface engineered phosphorene using boron and arsenic doping/Co-doping for Co-optimizing the adsorption stability, transduction, and recovery of CO, NO, and SO gases – A density functional theory perspective

In this work, for the first time, the effects of non-metallic Boron (B), Arsenic (As) substitutional doping as well as co-doping at different lattice positions of monolayer Phosphorene (Ph) have been extensively investigated for Carbon Monoxide (CO), Sulphur Monoxide (SO), and Nitrogen Monoxide (NO) adsorption using first principle calculation. The electronic configurations and effects of relative dopant positions (for co-doping) on atomic sub-planes of Ph significantly influence the molecular adsorptions of these monoxides, whereas the charge transfer is dominated by the molecular orientations and charge distributions of the gas molecule and host atoms near adsorption sites. The B doping notably increases the adsorption strength for each monoxide, wherein As doping increases the adsorption for CO and NO adsorption and reduces the strength for SO compared to pristine Ph. In contrast, B/As co-doping significantly and moderately increases the strength of CO/NO and SO adsorption, respectively. The co-doping exhibits a shorter recovery time while retaining adsorption stability for CO and NO. Moreover, doping/co-doping notably increases the charge transfer after NO adsorption. Finally, the NO and SO adsorptions severely alter the distribution of electronic states near the band edges, which results in significant modulations in the energy band structure of the co-doped lattice.

Equilibrium and kinetic isotope effects in heterogeneous catalysis: A density functional theory perspective

Equilibrium and kinetic isotope effects in heterogeneous catalysis: A density functional theory perspective

Rectangular Transition Metal-rTCNQ Organic Frameworks Enabling Polysulfide Anchoring and Fast Electrocatalytic Activity in Li-Sulfur Batteries: A Density Functional Theory Perspective

Two-dimensional metal-organic frameworks (MOFs) have shown great development po-tential in the field of lithium-sulfur (Li-S) batteries. In this theoretical research work, we propose a novel 3d transition metals (TM)-embedded rectangular tetracyanoquinodimethane (TM-rTCNQ) as a potential high-performance sulfur host. The calculated results show that all TM-rTCNQ structures have excellent structural stability and metallic properties. Through exploring different adsorption patterns, we discovered that TM-rTCNQ (TM = V, Cr, Mn, Fe and Co) monolayers possess moderate adsorption strength for all polysulfide species, which is mainly due to the existence of the TM-N4 active center in these frame systems. Especially for the non-synthesized V-rCTNQ, the theoretical calculation fully predicts that the material has the most suitable adsorption strength for polysul-fides, excellent charging-discharging reaction and Li-ion diffusion performance. Additionally, Mn-rTCNQ, which has been synthesized experimentally, is also suitable for further experimental con-firmation. These findings not only provide novel MOFs for promoting the commercialization of Li-S batteries, but also provide unique insights for fully understanding their catalytic reaction mecha-nism.

Research progress of transition-metal dichalcogenides for the hydrogen evolution reaction

In this review, five common preparation methods of TMDs are summarized, and then the mechanisms of five regulatory strategies are analyzed from the perspective of density functional theory, suggesting the potential of TMDs as HER electrocatalysts.

Dielectric response of confined water films from a classical density functional theory perspective.

We re-examine the problem of the dielectric response of highly polar liquids such as water in confinement between two walls using simple two-variable density functional theory involving number and polarisation densities. In the longitudinal polarisation case where a perturbing field is applied perpendicularly to the walls, we show that the notion of the local dielectric constant, although ill-defined at a microscopic level, makes sense when coarse-graining over the typical size of a particle is introduced. The approach makes it possible to study the effective dielectric response of thin liquid films of various thicknesses in connection with the recent experiments of Fumagalli et al., [Science, 2018, 360, 1339-1342], and to discuss the notion of the interfacial dielectric constant. We argue that the observed properties as a function of slab dimensions, in particular the very low dielectric constants of the order of 2-3 measured for thin slabs of ∼1 nm thickness do not highlight any special properties of water but can be recovered for a generic polar solvent having similar particle size and the same high dielectric constant. Regarding the transverse polarisation case where the perturbing field is parallel to the walls, the associated effective dielectric constant as a function of slab dimensions reaches bulk-like values at much shorter widths than in the longitudinal case. In both cases, we find an oscillatory behaviour for slab thicknesses in the one nanometer range due to packing effects.

New insights into the depression performance and mechanism of Fe(III) ion on the sulfidation of smithsonite: A DFT perspective

In this work, we have innovatively performed density functional theory (DFT) calculations on surface structures, adsorption structures, and electronic properties of smithsonite surface to study the depression mechanism of Fe(III) ion on the sulfidation of smithsonite. We found that the pre-adsorption of Fe(III) ion greatly reduced the reactivity of the surface of smithsonite, and the adsorption energies for HS on smithsonite surface with Fe(III) ion pre-adsorption were evidently less exothermic than those without Fe(III) ion pre-adsorption. In addition, we found that the resulting FeS bonds on Fe(III) ion pre-adsorbed smithsonite surface were weaker and more unstable compared with the ZnS bonds on the surface without Fe(III) ion pre-adsorption. Moreover, we found that without Fe(III) ion pre-adsorption, the hindrance of the hydration shell on smithsonite surface to HS was relatively small. However, with Fe(III) ion pre-adsorption, the hindrance of the hydration shell on smithsonite surface to HS became stronger. Thus, the sulfidation of smithsonite was depressed by Fe(III). This work uncovers the inhibition performance and mechanism of Fe(III) ion on the sulfidation of smithsonite at the microcosmic scale, which can help understand the depression effect of Fe(III) ion on the sulfidation of smithsonite in more depth.

Density Functional Theory Perspective on the Nonlinear Response of Correlated Electrons across Temperature Regimes.

We explore a new formalism to study the nonlinear electronic density response based on Kohn–Sham density functional theory (KS-DFT) at partially and strongly quantum degenerate regimes. It is demonstrated that the KS-DFT calculations are able to accurately reproduce the available path integral Monte Carlo simulation results at temperatures relevant for warm dense matter research. The existing analytical results for the quadratic and cubic response functions are rigorously tested. It is demonstrated that the analytical results for the quadratic response function closely agree with the KS-DFT data. Furthermore, the performed analysis reveals that currently available analytical formulas for the cubic response function are not able to describe simulation results, neither qualitatively nor quantitatively, at small wavenumbers q < 2qF, with qF being the Fermi wavenumber. The results show that KS-DFT can be used to describe warm dense matter that is strongly perturbed by an external field with remarkable accuracy. Furthermore, it is demonstrated that KS-DFT constitutes a valuable tool to guide the development of the nonlinear response theory of correlated quantum electrons from ambient to extreme conditions. This opens up new avenues to study nonlinear effects in a gamut of different contexts at conditions that cannot be accessed with previously used path integral Monte Carlo methods.

Glycerol and malonic acid as corrosion inhibitors seen through the density functional theory perspective

Glycerol (G) is the major co-product in the transesterification process of biodiesel. As clean energy demand increases, the production of G also increases and new ways of re-using it are needed. In the last decade, some experimental studies claimed that G and its derivative, malonic acid (MA), could be used as corrosion inhibitors. Yet, presently, there is little evidence of it and more studies are needed to confirm that G and MA could have a good performance in metal protection. The present work aims to study the reactivity of G and MA, since reactivity and inhibition are intimately linked. The density functional theory (DFT) at the B3YLP/6-31G** level of theory was used to study the reactivity of both molecules. The global and local quantum parameters derived were used to assess the reactivity of both molecules. Analysis of the calculated reactivity descriptors suggest that G and MA should exhibit an acceptable corrosion efficiency, but MA showed have a greater potential as a corrosion inhibitor.

Catalytic oxidation of NO to NO2 on pure and doped AunPt3-n (n=0–3) clusters: A DFT perspective

A systematic density functional theory (DFT) calculations are performed on pure as well as doped Au3 trimer clusters to study the catalytic oxidation of NO to NO2 using the M06L functional combined with a def2QZVPP basis set. Adsorption energies and Bader charges of adsorbed NO and O2 on the AunPt3-n clusters have been calculated to observe the stability of the adsorbed species. Results show that the adsorption of both NO and O2 on the bimetallic clusters is stronger on the Pt site than that of Au site. Owing to the high adsorption energy of both the reactants, we further propose a reaction mechanism of NO oxidation over AunPt3-n (n = 0–3) clusters following the Langmuir-Hinshelwood (L-H) mechanism. The rate constants of NO2 production at each step of the reaction mechanism are determined using the Transition State Theory (TST). Energetic span model is also used to determine the efficient catalytic system among the four clusters. This study offers a new insight into the fundamental effect of doping Pt on Au3 and conveys an understanding for the NO oxidation mechanism at the molecular level which in turn will help in building efficient catalysts for large-scale processes.

Phase driven magnetic and optoelectronic properties of La2CrNiO6: A DFT and Monte Carlo perspective

In search of the ferromagnetic insulators for spintronic device applications, we have studied the electronic, optical and magnetic properties of La2CrNiO6 (LCNO) using the first principle density functional theory (DFT) and the Monte Carlo simulation technique. Firstly, we have adopted the sol-gel method for the preparation of LCNO and refined the X-ray diffracted value using the Fullprof suite under the Rietveld mechanism. The obtained orthorhombic Pbnm and cubic Fm-3m space groups are used as the input of the DFT calculations. Both the structures have shown the half metallicity and insulting bandgap towards the majority and minority spin direction, respectively. From the magnetic moment calculations, we have seen the low spin state of Ni3+, and the double exchange (DE) interaction are responsible for the ferromagnetic structure of LCNO. The optical dielectric constant is ten, and the refractive index is 3.2 for orthorhombic structure. The transition temperature (TC) is determined to be 110 ​K from the MCS study, which has well agreed with experimental value (111 ​K). The RCP value is determined to 12 ​J/kg with a 5 ​T applied field, which is good for magnetocaloric applications.

Characterization of novel pyridine‐derived N‐heterocyclic silylenes via density functional theory perspective

AbstractWe theoretically searched new derivatives of N‐heterocyclic silylenes (NHSis) by substituting of pyridine and phosphinine rings, compared to the reference carbenes (N‐heterocyclic carbenes—NHCs) including benzopyridine‐4‐ylidene (1) and dibenzopyridine‐4‐ylidene (2), at M06‐2X/AUG‐cc‐pVTZ and B3LYP/AUG‐cc‐pVTZ. Regardless of how organized NHSis are, fusion of 1 six‐membered ring leads to more vibration frequency (υmin), stabilizing effect, and polarizability than 2 six‐membered rings. In all cases, singlet (3s‐10s) and triplet (3t‐10t) NHSis emerge as ground state, showing more stability of singlet states than their corresponding triplet congeners. From thermodynamic and kinetic viewpoints, the scrutinized singlet NHSis show more stability than the parent singlet NHCs (1s and 2s), but the studied triplet NHSis exhibit less stability than triplet NHCs (1t and 2t). Regarding the orientation of silylenic center and nitrogen or phosphor heteroatoms of fused rings, the stabilizing energy for para−fused rings is more than ortho ones. The most stability is confirmed by one para−substituted pyridine NHSi (singlet‐triplet energy difference; ΔΕs‐t = 47.3 and band gap; ΔEHOMO‐LUMO = 85.0 kcal/mol; highest occupied molecular orbital [HOMO] and lowest unoccupied molecular orbital [LUMO]) and the least stability is demonstrated by two substituted benzene NHC (ΔΕs‐t = 11.9 and ΔEHOMO‐LUMO = 58.6 kcal/mol). In contrast to pure NHCs, triplet NHSis (3t‐10t) show lower ΔΕHOMO‐LUMO, higher nucleophilicity, lower electrophilicity, and lower chemical hardness than their corresponding singlet states (3s‐10s).

Effects of Uniaxial Lattice Strain and Explicit Water Solvation on CO2 Electroreduction over a Cu Electrode: A Density Functional Theory Perspective

Strain engineering of metal-based catalysts has emerged as an efficient solution to breaking of scaling relations of adsorbed species in a catalytic reaction. However, many aspects of the fundament...