Density Functional Theory Approach Research Articles

2,4-dichloro-6-(1,4,5-triphenyl-1H-imidazol-2-yl) phenol: synthesis, DFT analysis, Molecular docking, molecular dynamics, ADMET properties against COVID-19 main protease (Mpro: 6WCF/6Y84/6LU7)

ABSTRACT New derivatives of 2,4-dichloro-6-(1,4,5-triphenyl-1H-imidazol-2-yl) phenol (DPIP) have been successfully synthesised and characterised using spectral methods such as FT-IR, 1H NMR and 13C NMR. Density functional theory (DFT) approach at B3LYP/6-311 G (d, p) level of theory is used to determine optimised bond parameters and single crystal XRD investigation of related derivatives confirms the structure of DPIP bond parameters. The single crystal XRD measurements and the optimised geometrical parameters produced by the DFT calculation agree well. The FT-IR bands seen in the experiment were attributed to distinct normal modes of the molecule. Frontier molecular orbital computations described the molecule stability, chemical reactivity and charge transfer. Atomic charges determined via Mulliken population analysis on the different DPIP atoms. MEP, which is mapped to the electron density surfaces, has discovered potential reactive sites of the molecule. The reported molecule is used as a potential NLO material since it has a high μβ0 value. Binding affinities were discovered using molecular docking against the COVID-19 major protease (Mpro: 6WCF/6Y84/6LU7). The behaviour of the complex structure formed by the Covid-19 protein under in silico physiological conditions was then confirmed by a 100 ns molecular dynamic simulation which looked at the structure stability over time and revealed a stable conformation and binding pattern in an environment of imidazole derivatives. Furthermore, favourable to moderate anti-viral activity was revealed by an in-silico analysis that anticipated the compound absorption, distribution, metabolism, excretion and toxicity profiles (ADMET).

Tailoring the Electronic Structures and Spectral Properties of ZnO with Irradiation Defects Generated Under Intense Electronic Excitation: A Combined Experimental and DFT Approach

AbstractThe relationship between the composition of the internal defect states, spectral properties, and correlated electronic structures of wurtzite zinc oxide (ZnO) crystals under 645 MeV Xe35+ irradiation is systematically investigated, employing experimental characterizations combined with first‐principle calculations. Based on the ion irradiation‐induced thermal expansion and relaxation processes, the high concentration of vacancy/interstitial defects produced from the transient disordered phase in molten track states trigger photoelectric changes, as follows: i) the generation of internal defect states effectively reduces the intrinsic bandgap (3.25 eV → 2.66 eV); ii) a large number of defective active sites inhibits the recombination between electron–hole pairs, causing dark conductance and photoconductance to increase with increasing damage levels until optimal fluence is achieved. Based on the density functional theory (DFT) with the GGA + U (GGA = generalized gradient approximation) method, the defective models associated with the different electronic structures, density of states, formation energy, and the nature of the chemical bonding are established. The narrowing of the bandgap observed experimentally and the enhancement of carrier concentration originating from the internal electron defect states are qualitatively verified, therefore laying the foundation for designing future nanoscale photoelectronic devices and microelectronics applications.

Tuning the potentials of aluminum phosphide nanotube photocatalyst for wastewater treatment through band gap engineering: a DFT study

Abstract The photocatalytic properties of semiconductor materials, which are controllable through the design of the bandgap structure, make them a promising catalyst for wastewater treatment. This work investigated the photocatalytic properties of single-walled aluminum phosphide nanotube (SWAlPNT) doped with different concentrations of boron (B) atoms for wastewater treatment. Analysis of the structural, electronic and optical properties of the SWAlPNT photocatalyst was performed using the density functional theory approach in terms of plane wave basis set and pseudopotential. The SWAlPNT was found to be stable to B doping with 3.6% and 7.1% concentrations. Cohesive energy decreases with an increase in concentration of dopant which results in efficient thermal stability. An indirect band gap value of 1.4 eV was obtained with B-doped SWAlPNT with 3.6% concentration which agreed with band gaps of other photocatalysts used for wastewater purification. Analysis using optical absorption spectra revealed that 3.6% B-doped system absorbs visible light while 7.1% doped system absorbs both visible and ultraviolet light. This study found both 3.6% and 7.1% B-doped SWAlPNT as suitable photocatalysts for wastewater treatment under solar irradiation, while the 3.6% B-doped system shows relatively better performance for wastewater treatment.

Computational study on the endocrine-disrupting metabolic activation of Benzophenone-3 catalyzed by cytochrome P450 1A1: A QM/MM approach

Predicting the metabolic activation mechanism and potential hazardous metabolites of environmental endocrine-disruptors is a challenging and significant task in risk assessment. Here the metabolic activation mechanism of benzophenone-3 catalyzed by P450 1A1 was investigated by using Molecular Dynamics, Quantum Mechanics/Molecular Mechanics and Density Functional Theory approaches. Two elementary reactions involved in the metabolic activation of BP-3 with P450 1A1: electrophilic addition and hydrogen abstraction reactions were both discussed. Further conversion reactions of epoxidation products, ketone products and the formaldehyde formation reaction were investigated in the non-enzymatic environment based on previous experimental reports. Binding affinities analysis of benzophenone-3 and its metabolites to sex hormone binding globulin indirectly demonstrates that they all exhibit endocrine-disrupting property. Toxic analysis shows that the eco-toxicity and bioaccumulation values of the benzophenone-3 metabolites are much lower than those of benzophenone-3. However, the metabolites are found to have skin-sensitization effects. The present study provides a deep insight into the biotransformation process of benzophenone-3 catalyzed by P450 1A1 and alerts us to pay attention to the adverse effects of benzophenone-3 and its metabolites in human livers.

Study of structural, dynamical stability, electronic magnetic and optical properties of RbSnO3 oxide perovskite compound using the density functional theory approach

This study investigates the structural, phonon, elastic, electronic, magnetic and optical properties of cubic perovskite RbSnO3. The calculations are based on the linearized augmented plane wave method with total potential (FP-LAPW), implemented in the Wien2k code; two approximations are used for calculate properties, PBE-GGA and TB-mBJ . The values of the tolerance factor and the formation energy of this material indicate that it is stable in the cubic structure of Pm3̅m symmetry. The Born criteria for the compound under study confirm its mechanical stability, while its phonon dispersion curves confirm its dynamic stability. The results of the electronic and magnetic properties show that the compound is ferromagnetic (FM) semi-metallic (DM) with semiconductor behavior in the majority spin channel and with an indirect gap in the M → Γ direction and having a total magnetic moment equal to 1 μB and a Curie temperature equal to 527 K. Optical spectra of the compound show high optical conductivity in the infrared region and towards the end of the spectrum at around 6 eV, high reflection in the infrared region with a maximum at 0.25 eV, and high absorption in the ultraviolet region at 6 eV. In view of these results, the RbSnO3 perovskite can be a promising candidate for spintronics applications as it can be used in optical devices working in the ultraviolet (UV) light region.

Unleashing the power of artificial intelligence in phonon thermal transport: Current challenges and prospects

The discovery of advanced thermal materials with exceptional phonon properties drives technological advancements, impacting innovations from electronics to superconductors. Understanding the intricate relationship between composition, structure, and phonon thermal transport properties is crucial for speeding up such discovery. Exploring innovative materials involves navigating vast design spaces and considering chemical and structural factors on multiple scales and modalities. Artificial intelligence (AI) is transforming science and engineering and poised to transform discovery and innovation. This era offers a unique opportunity to establish a new paradigm for the discovery of advanced materials by leveraging databases, simulations, and accumulated knowledge, venturing into experimental frontiers, and incorporating cutting-edge AI technologies. In this perspective, first, the general approach of density functional theory (DFT) coupled with phonon Boltzmann transport equation (BTE) for predicting comprehensive phonon properties will be reviewed. Then, to circumvent the extremely computationally demanding DFT + BTE approach, some early studies and progress of deploying AI/machine learning (ML) models to phonon thermal transport in the context of structure–phonon property relationship prediction will be presented, and their limitations will also be discussed. Finally, a summary of current challenges and an outlook of future trends will be given. Further development of incorporating AI/ML algorithms for phonon thermal transport could range from phonon database construction to universal machine learning potential training, to inverse design of materials with target phonon properties and to extend ML models beyond traditional phonons.

Transesterification of Dimethyl Carbonate with Ethanol Catalyzed by Guanidine: A Theoretical Analysis.

Density-functional theory (DFT) was performed to investigate the mechanistic features of different guanidine-based catalysts, namely, 1,1,3,3-tetramethyl guanidine (TMG) and 1,5,7-triaza-bicyclo-[4.4.0]dec-5-ene (TBD), for the transesterification reaction of dimethyl carbonate (DMC) with ethanol (EtOH). Different possible pathways were suggested in which these catalysts act as either nucleophile or base within a homogeneous system. The DFT results allowed not only the study of the thermochemistry aspects of all elementary reactions featured in the two different activation modes but also the accurate calculation of the free energy barriers for each case. Our findings showed that the catalyzed reaction proceeded through simultaneous activation of DMC and EtOH, facilitated by hydrogen bonding for both catalysts. This feature led to the formation of a stable intermediate with a relatively low free energy barrier. TBD exhibited a potentially more efficient mechanism, owing to its planar structure and dual-activation mode. The free energy barrier of the rate-limiting step, identified as the formation of a zwitterionic complex, then declined by approximately 50% when compared with the reaction without catalysts. Overall, the DFT approach provides good insight into the reactivity of both catalysts and helps to find possibilities for further enhancing the mechanistic features of both catalysts for this type of transesterification reaction.

Orbital-Optimized Versus Time-Dependent Density Functional Calculations of Intramolecular Charge Transfer Excited States.

The performance of time-independent, orbital-optimized calculations of excited states is assessed with respect to charge transfer excitations in organic molecules in comparison to the linear-response time-dependent density functional theory (TD-DFT) approach. A direct optimization method to converge on saddle points of the electronic energy surface is used to carry out calculations with the local density approximation (LDA) and the generalized gradient approximation (GGA) functionals PBE and BLYP for a set of 27 excitations in 15 molecules. The time-independent approach is fully variational and provides a relaxed excited state electron density from which the extent of charge transfer is quantified. The TD-DFT calculations are generally found to provide larger charge transfer distances compared to the orbital-optimized calculations, even when including orbital relaxation effects with the Z-vector method. While the error on the excitation energy relative to theoretical best estimates is found to increase with the extent of charge transfer up to ca. -2 eV for TD-DFT, no correlation is observed for the orbital-optimized approach. The orbital-optimized calculations with the LDA and the GGA functionals provide a mean absolute error of ∼0.7 eV, outperforming TD-DFT with both local and global hybrid functionals for excitations with a long-range charge transfer character. Orbital-optimized calculations with the global hybrid functional B3LYP and the range-separated hybrid functional CAM-B3LYP on a selection of states with short- and long-range charge transfer indicate that inclusion of exact exchange has a small effect on the charge transfer distance, while it significantly improves the excitation energy, with the best-performing functional CAM-B3LYP providing an absolute error typically around 0.15 eV.

Computational investigation of hydrogen evolution reaction on transition metal-doped monolayer VSe2: A DFT approach

Density functional theory (DFT) was used to investigate the hydrogen evolution reaction (HER) on monolayer VSe2 doped by transition metal (TM) (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rh, Ir), in which Se or V is replaced by TM atoms (denoted as TM@Se or TM@V). Introducing transition metals (TMs) into the VSe2 monolayer can alter its electronic structure and catalytic properties. The choice of transition metal dopants and their configurations can significantly impact the catalytic performance of the material. It is illustrated that the TM@V systems are more stable than TM@Se configurations. Moreover, Co@V, Cu@V, Fe@V Zn@V and Cu@Se exhibit the lower ΔGH* values of 0.07, 0.09, 0.10, 0.12 and −0.1 eV, respectively, and ΔGH* values are very close to the ideal value of zero and are superior to precious metal Pt (ΔGH* = −0.1eV). Based on the scaling relationship of ΔGH* of H* intermediate, the volcano diagram and exchange current density diagram are established. It is predicted that Cu@V, Co@V, Fe@V, Zn@V structures could provide large exchange current of −1.6, −1.22, −1.7, −2 i0/(Acm−2), respectively.

Study of mechanical, optoelectronic, and thermoelectric properties of Rb2ScAuZ6 (Z = Br, I) for energy harvesting applications

In the current article, the structural, mechanical, optoelectronic, and thermoelectric properties of Rb2ScAuZ6 (Z = Br, I) have been predicted using the density functional theory (DFT) approach. The tolerance factor, phonopy, and formation energy analysis validated the structural, dynamic, and thermodynamic stability of Rb2ScAuBr6 and Rb2ScAuI6, respectively. Likewise, the investigated elastic properties concluded that both materials exhibit mechanical stability and possess ductile characteristics. The directional-dependent elastic moduli revealed the anisotropy features. The indirect bandgaps determined by TB-mBJ approximation are 2.1 eV and 1.6 eV for Rb2ScAuBr6 and Rb2ScAuI6, respectively. Optical absorption, reflectivity, refractive index, and dielectric constants have been assessed in the energy range between 0 and 6 eV to ensure efficient absorption in the visible spectrum. Both materials have appropriate optical parameters for utilization in photovoltaic systems. Further, using the BoltzTraP code, the thermoelectric properties have been calculated to evaluate the thermoelectric efficiency. Both perovskites have lower lattice and electronic thermal conductivity, a higher Seebeck coefficient, and a higher figure of merit, making them ideal candidates for thermoelectric applications.

Mechanistic Insights into the Palladium-Catalyzed Perfluoroalkylative Carbonylation of Unactivated Alkenes to β-Perfluoroalkyl Esters: A DFT Study.

Transition metal-catalyzed multicomponent carbonylation is an efficient synthetic strategy to access multifunctional esters in high yields with broad functional group tolerance and good chemoselectivity. Considering the development of highly efficient synthetic methods for esters, it remains significant to grasp the mechanism of constructing multifunctional esters. Herein, density functional theoretical calculations were carried out to acquire mechanistic insight into the synthesis of β-perfluoroalkyl esters from a specific palladium-catalyzed perfluoroalkylative carbonylation of unactivated alkenes using carbon monoxide. A detailed mechanistic understanding of this reaction route includes (1) multistep radical reaction process, (2) C-C coupling and CO insertion, (3) ligand exchange, and (4) Pd-based intermediate oxidation and reductive elimination. The multistep radical process was fundamentally rationalized, including Rf· formation and radicals A and E from unactivated alkene and CO oxidation, respectively. The potential energy calculation indicated that the CO insertion into the perfluorinated alkyl radicals preceded Pd-catalyzed oxidation in the competitively multistep free radical reaction process. In addition, the I-/PhO- exchange step was predicted to be spontaneous to products. The IGMH analysis further attested to the reductive elimination process involved in the rate-determining step. Thus, a simple and valid density functional theory (DFT) approach was developed to reveal the multistep radical mechanism for the Pd-catalyzed perfluoroalkylative carbonylation of unactivated alkenes to access functional β-perfluoroalkyl esters.

Exploring Curcumin Interaction with PLGA Nanoparticles via Various Functional Groups: A Dispersion-Corrected Density Functional Theory and Molecular Dynamics Simulation Approach

Density functional theory (DFT)-D3 dispersion corrections and molecular dynamic (MD) techniques were used to research how curcumin (CUR) and poly (lactic-co-glycolic acid) (PLGA) interact in the water phase. Relaxation based on machine learning (ML) algorithms was used to identify the state configuration that was the most stable. The electronic, optical, and infrared (IR) vibrational properties of the studied configurations were then computed. The findings show that since PLGA nanoparticle can transport CUR via chemical interactions, the binding energy of CUR through carbonyl group to PLGA is about -1.092eV (complex A). The theoretical IR spectrum supports the observation that the functional groups of CUR interacting with PLGA undergo changes, which is consistent with the experimental data. Hence, the Bader charge analysis indicates a charge of about 0.14 (complex A) and 0.17 (complex B) |e| transferred from the PLGA to CUR. The charges in CUR exhibit strong charge transfer to the PLGA structure. The calculated results of the CUR-PLGA complex match the main peak in the 500-580nm range observed in experiments, and the stable optimal optical absorption diagram aligns with the reported spectra. The total density of states (TDOS) of the studied configurations shows that CUR is having an impact on the HOMO and LUMO levels. The PLGA nanoparticle demonstrates a higher sensitivity (86%) towards the presence of CUR in complex D compared to complex B (67%), which can be attributed to the change in the energy gap. This low adsorption energy and high sensitivity suggest that the PLGA nanoparticle indicates its potential to serve as both a carrier and a sensor for detecting CUR in the water phase.

Morphological, Structural and Electronic properties of Zinc Oxide Nano Structures Deposited on ZnO Substrate Layer–A Theoretical Perspective

The work investigates the deposition of zinc and oxygen atoms on a Zinc terminated ZnO substrate, maintaining their stoichiometric ratio (O:Zn) at 0.8, under varying incident energies (0.5eV and 5eV) and temperatures (300K and 700K) using the ReaxFF potential in Molecular Dynamics (MD) simulation. The study explores the impact of deposition conditions on growth mechanisms, film morphology, and structural parameters such as Radial Distribution Function (RDF) and Coordination Number (CN). RDF analysis highlights disordered atomic arrangements and diverse bonding configurations within the film, with CN showing deviations from perfect crystalline ZnO, indicating non-uniform, non-crystalline, and nano behaviour. Post-heating the films to temperatures approaching the ZnO melting point results in enhanced crystallinity, as evidenced by distinct, dominant, and multiple RDF peaks. Density Functional Theory (DFT) approach of the deposited structures elucidates the formation of ZnO nanoclusters-(ZnO)3 and (ZnO)4 and investigates their electronic structure properties. DFT analysis of the post-heated films reveals the formation of ZnO monomers (ZnO), indicating an approaching crystalline behaviour, yet the films exhibit non-epitaxial and non-uniform characteristics. DFT calculations were instrumental in validating the observed structural behaviours in the deposited films. The study underscores the significance of stoichiometric ratio in film deposition and demonstrates the temperature-dependent evolution of structural properties towards crystallinity, shedding light on the intricate dynamics of ZnO film growth offering tailored control over film properties for enhanced performance in practical applications such as optoelectronics and gas sensing.

Unveiling the Electronic Structure of SnS for Photocatalytic Applications: A DFT Approach†

AbstractPhotocatalytic materials are of great scientific interest due to their potential applications in sustainable energy sources. Band gap and optical absorption of the materials are two core characteristics for photocatalysis that eventually depend on electronic structure. In order to accurately compute (predict) the electronic‐scale properties of a crystalline solid using first principles calculations, which might be costly to measure experimentally, large‐scale atomic level calculation frameworks have been made possible through the use of density functional theory (DFT). We have used DFT with many body perturbation theory (MBPT) by solving the bethe‐salpeter equation (BSE) to priorly predict the properties of bulk tin sulfide (SnS) as it meets the necessary requirements for photocatalytic applications. We fixed the DFT band gap underestimation by including the Hubbard parameter (U) and used projector augmented wave pseudo‐potentials with generalized‐gradient approximation (GGA) to calculate the electronic and optical properties of SnS. Optical properties were computed using independent particle approximation (IPA) and BSE with DFT+U wave functions. Our theoretical results align with experimental data for this material, demonstrating the potential for further research in validating experimental results with theoretical approximations and empirical relations.

DFT insights into i-MAB phase, Mo4Y2Al3B6: a potential thermal barrier coating and solar heat reducing material

We have investigated the physical properties of the i-MAB: Mo4Y2Al3B6 phase via the density functional theory (DFT) approach. The optical properties, thermal properties, and Vickers hardness of the compound Mo4Y2Al3B6 have been studied theoretically for the first time. The correctness of the fine-tuned structural parameters is confirmed by their close match with experimental results. The compound’s metallic nature is established by an analysis of its electronic band structure, which is demonstrated by the overlap of the valence and conduction bands at the Fermi level. The mechanical and dynamic stability of the compound is supported by the single crystal elastic constants and computed phonon dispersion curve. The brittleness and machinability index has been studied to predict its usefulness in any form/shape. The compound’s ability to be exfoliated into 2D nanosheets has been proven by the f-index value. The obtained Vickers hardness value indicate the materials’ softness and ease of machining, aligning with the experimental findings. The thermodynamic properties are evaluated through phonon dispersion curves, including Debye temperature, free energy, enthalpy, entropy, and specific heat capacity. The potential of Mo4Y2Al3B6 as a thermal barrier coating (TBC) material is demonstrated by its low minimum thermal conductivity (K min), low volume expansion coefficient and high melting temperature (T m ). Key optical parameters, including dielectric functions, refractive index, photoconductivity, reflectivity, absorption coefficient, and loss function, have been computed and analyzed. The reflectivity spectrum suggests that the titled compound acts as a promising coating material for mitigating solar heating.

Oxidation of thiram fungicide by hydroxyl radicals in water: A theoretical study on reaction mechanism and kinetics

AbstractThe oxidation of thiram (THR) pesticide initiated by HO• radicals in water was investigated using the density functional theory (DFT) approach at the M06‐2X/6‐311++G(3df,3pd)//M06‐2X/6‐31+G(d,p) level of theory. Three oxidation mechanisms were evaluated: radical addition, hydrogen abstraction, and single electron transfer. The results showed that all these reactions are favorable and spontaneous. Among them, the addition reactions at S‐positions have the most prominent rate constants and branching ratios. In addition, the oxidation of THR is temperature‐dependent; the higher the temperature, the faster the oxidation and the higher the removal efficiency. The overall rate constant is k(T) = 7.816 × 10−6 × T5.953 × exp[929.0 (J mol−1)/(RT)] (M−1 s−1), showing a rate constant of 6.09 × 109 m−1 s−1 at 298.15 K which agrees with the previously reported experimental result. In general, thiram can be easily decomposed in a wastewater treatment process with a high concentration of HO•. Still, it may exist in a natural‐like environment with a very low HO• concentration from a few days to several years.

Transition metals vs. chalcogens: The impact on NOx adsorption on MoS2, MoSe2 and WS2 transition-metal dichalcogenides

The widely developed industry of today generates significant amounts of harmful gases, which prompts the search for modern materials allowing for their efficient and reliable detection. Transition-metal dichalcogenides (TMD) constitute well-known example of such, with particularly high potential for excellent sensing of NO2. It is known, that the adsorption of this hazardous molecule varies on the TMD composition, however the importance of transition metal and chalcogen types were never previously contrasted. Moreover, the other NOx compounds, namely NO and N2, interact much less with TMD sheets, the reason for which is not yet well understood. This work utilizes density functional theory (DFT) approach to untangle these problems by examining the adsorption processes of NO2, NO, and N2 on the monolayers of WS2, MoS2, and MoSe2. The calculations allowed to establish two important conclusions: (i) the chalcogen is significantly more important than transition metal, allowing for much greater increase in adsorption of NO2 on MoSe2 than on WS2, as compared to that on MoS2, (ii) only molecules acting as an acceptor with respect to the TMD sheet can benefit from the enhancement coming from the composition of the latter. The gained insight can likely contribute to the informed design of devices allowing selective detection, the lack of which is a recognized problem among semiconductor sensors.

Asymmetric naphthalene centred bis-ester Schiff base: Self-assembling behaviour and DFT approach

New asymmetric 2,6-disubstituted naphthalene embedded Schiff base-bis esters NEKE-(2–18) synthesized and investigated for their mesomorphic behaviour. One end of naphthalene has been substituted by decyloxy long chain whereas the other end connected with imine-bis ester aromatic core with terminal long chains. New molecules have been found to exhibit polymorphic behaviour with good thermal stability and enhanced mesophase stability upon POM (polarising optical microscopy) and DSC (differential scaling calorimetry) investigations. Early members (C2 and C3) showed nematogenic behaviour along with SmA (smectic-A) mesophase, whereas molecules with C4 and C5 showed only SmA phase. Compounds with C6 and C7 showed monotropic SmC (smectic-C) upon cooling whereas molecules from C8-to-C18 exhibited enantiotropic SmC along with SmA mesophase. The presence of mesophase has been confirmed by VT-XRD (variable temperature X-ray-crystallography) analysis. For comparison and better understanding, the mesomorphic data of compounds from literature has been compared. The DFT (density functional theory) calculations were performed on both new compounds and structurally analogous molecules found in literature. A detailed discussion was carried out regarding the correlation between the mesomorphic behaviour observed in new compounds and literature, and the computed structural (length, aspect ratio) and electronic (dipole moment, polarizability) variables.

A DFT approach to explore the structural, optoelectronic, mechanical, and thermoelectric attributes of lead-free RbInX3 (X = I, Br, Cl) halide perovskites for renewable energy applications

Halide perovskites are significant due to their versatility and high performance in optoelectronics and green technologies. This paper thoroughly investigates the structural, elastic, optoelectronic and transport characteristics of RbInX3 (X = I, Br, Cl) perovskites using density functional theory (DFT) embedded in Wein2K. Modified Becke Johnson as an exchange correlation potential is used to evaluate the physical characteristics. Structural stability is achieved with the tolerance factor and octahedral tilting along with the optimization curves. A metallic character is detected in RbInI3. However, the replacement of I with Br and Cl atoms results in an indirect band gap of 0.9 eV and 1.95 eV at (L-X) symmetry points, respectively. The elastic constants are utilized to determine the elastic parameters that ensure the structural stability of perovskites. Cauchy pressure and Poisson’s ratio indicate the ductile nature of all studied phases. The thermal behavior is evaluated through the computation of Debye temperature. Furthermore, an insight into the material’s interaction with electromagnetic radiation is accessed through the optical parameters. A high absorption at 1.49 eV for RbInI3, 1.65 for RbInBr3 and 2.57 for RbInCl3 show their potential for light emitting devices. The semi-classical Boltzmann theory is employed to compute thermoelectric properties, which show RbInI3, RbInBr3 and RbInCl3 possess high electrical conductivities of 3.068 ×1019 S m–1, 1.88 ×1019 S m–1 and 1.76 ×1019 S m–1 at 1200 K, respectively. The ZT value for RbInBr3 is 0.74 and RbInCl3 is 0.73, while RbInI3 exhibit the lowest ZT of 0.04 at 1200 K. The examined characteristics indicate that RbInBr3 and RbInCl3 possess promising potential for renewable energy applications.

Hydrogen storage properties of Ti-doped C20 nanocage and its derivatives: A comprehensive density functional theory investigation

We have innovatively designed and assessed the hydrogen storage properties of a single Ti-doped C20 nanocage and its B, N or B and N heteroatom substituted derivatives with the help of the density functional theory approach for the first time to the best of our knowledge. Out of fifteen designed structures by substituting heteroatoms, only 8 structures are found to be suitable for Ti doping and H2 adsorption viz. C20, C12N8, C12B8, C12B4N4, C10B5N5, C10B10, B10C10 and B10N10. Their formation energy and cohesive energy values confirm the stability of all the structures. Ti atom binds more strongly with B, N or B and N heteroatom substituted C20 nanocage than unsubstituted C20 nanocage which is necessary to avoid clustering for multiple Ti doped nanocages. Among the eight Ti doped nanocages considered, H2 molecules strongly interact with Ti-doped C12B4N4 nanocage. The binding strength of Ti atom with nanocages decreases during the hydrogen adsorption process. The obtained H2 adsorption energy values for all the structures are within the range of 0.2–0.7 eV, which is conducive to reversible hydrogen storage. Calculated Gibbs free energy-corrected H2 adsorption energy values at different temperature and pressure indicate favorable H2 adsorption over the entire pressure range at room temperature. For Ti doped C20, C12N8, C12B8, C10B5N5, C10B10, B10N10, and B10C10 nanocages, H2 adsorption is thermodynamically favorable below 360, 350, 300, 285, 235, 277, and 251 K, respectively at 1 atm pressure. From PDOS analysis, it is observed that the 1s orbital of H overlaps with 3d orbital of Ti atom. The highest H2 desorption temperature is observed for the C12B4N4Ti nanocage, and the lowest for C10B10Ti, aligning well with the calculated adsorption energy values. As H2 desorption temperature is high, the stability of Ti-doped nanocages at high temperature (634 K) is confirmed using ab initio molecular dynamics simulations. Bader's quantum theory in atoms in molecules is used to prove the weak non-covalent interaction between all the atoms.