Overlap Population Research Articles

Investigating the microscopic enhancement mechanisms of adsorption-based CO2 capture with Cu-loaded γ−Al2O3 using density functional theory

Transition-metal-loaded γ−alumina (Al2O3) is considered to be an effective adsorbent for CO2 capture, but its microscopic process and mechanisms of CO2 adsorption are not fully understood. To investigate the microscopic enhancement role of Cu atoms in CO2 adsorption, this work compares various adsorption configurations and parameters of CO2 on γ−Al2O3 (110) facets with or without Cu atoms and small Cu cluster loading (Cun (n=1,2,3)/γ−Al2O3) using the first-principles approach. According to the adsorption energy, charge transfer, difference charge density, and other parameters of different configurations, the γ−Al2O3 (110) slab loaded with the Cu atom is found to exhibit enhanced adsorption of CO2 molecules compared to that without Cu loading. Moreover, the surface stability increases with the number of loaded Cu atoms. However, the hydroxyl groups in the active sites partially undermine the adsorption effect during the CO2 adsorption process. The density of states indicates that the doping of Cu atoms in the system creates an orbital peak closer to the Fermi energy level. This facilitates the transfer of charge within the slab, making the activation of CO2 easier and promoting stable adsorption. Finally, the amount of crystal orbital overlap population and crystal orbital Hamilton population shows that the stability of adsorption is due to the formation of C-Cu and C-Al bonds. It is demonstrated that the Cun-loaded γ−Al2O3 (110) slab improves the adsorption performance and contributes to a better understanding of the effect of transition-state metal loaded γ−Al2O3 on CO2 adsorption.

CO adsorption mechanisms on transition metal surfaces and factors influencing the adsorption

CO adsorption on transition metal (TM) surfaces has been extensively studied. Compared to the "vertical adsorption" (CO⊥M) in which the C–O bond is normal to the surface with the C bonded to the surface, few studies are devoted to the "parallel mode" (CO||M) where the C–O bond is (near) parallel to the surface with both C and O atoms interacting with the surface. Here we report density functional calculations of CO adsorption on the stable surfaces of 27 TMs. The results show that CO adsorbs only in CO⊥M mode on IB, IIB, VIIB and VIII TMs while both CO⊥M and CO||M modes exist on IIIB to VIB TMs, with CO||M being more stable. Overlap population analysis reveals that the interactions between metal d AOs and O 2p AOs dominate the CO||M mode where the CO π bond is greatly weakened, resulting in significantly activated CO. The adsorption mode and adsorption energy can be tuned by ensemble effect, lattice strain and crystal structure, while the ligand effect is weak and is not able to change the adsorption mode of CO. The present work demonstrates that ensemble effect, lattice strain and crystal structure can be utilized to modify surface chemistry and promote catalytic performance effectively.

Crystal orbital overlap population based on all-electron ab initio simulation with numeric atom-centered orbitals and its application to chemical-bonding analysis in Li-intercalated layered materials

Crystal orbital overlap population (COOP) is one of the effective tools for chemical-bonding analysis, and thus it has been utilized in the materials development and characterization. In this study, we developed a code to perform the COOP-based chemical-bonding analysis based on the wave function obtained from a first principles all-electron calculation with numeric atom-centered orbitals. The chemical-bonding analysis using the developed code was demonstrated for F2, Si, CaC6, and metals including Ti and Nb. Furthermore, we applied the method to analyze the chemical-bonding changes associated with a Li intercalation in three representative layered materials: graphite, MoS2, and ZrNCl, because of their great industrial importance, particularly for the applications in battery and superconducting materials. The COOP analysis provided some insights for understanding the intercalation mechanism and the stability of the intercalated materials from a chemical-bonding viewpoint.

Balancing versus modelling in weighted analysis of non-randomised studies with survival outcomes: A simulation study.

Weighting methods are widely used for causal effect estimation in non-randomised studies. In general, these methods use the propensity score (PS), the probability of receiving the treatment given the covariates, to arrive at the respective weights. All of these "modelling" methods actually optimize prediction of the respective outcome, which is, in the PS model, treatment assignment. However, this does not match with the actual aim of weighting, which is eliminating the association between covariates and treatment assignment. In the "balancing" approach, covariates are thus balanced directly by solving systems of numerical equations, explicitly without fitting a PS model. To compare modelling, balancing and hybrid approaches to weighting we performed a large simulation study for a binary treatment and a survival outcome. For maximal practical relevance all simulation parameters were selected after a systematic review of medical studies that used PS methods for analysis. We also introduce a new hybrid method that uses the idea of the covariate balancing propensity score and matching weights, thus avoiding extreme weights. In addition, we present a corrected robust variance estimator for some of the methods. Overall, our simulations results indicate that balancing approach methods work worse than expected. However, among the considered balancing methods, entropy balancing consistently outperforms the variance balancing approach. All methods estimating the average treatment effect in the overlap population perform well with very little bias and small standard errors even in settings with misspecified propensity score models. Finally, the coverage using the standard robust variance estimator was too high for all methods, with the proposed corrected robust variance estimator improving coverage in a variety of settings.

First-principles study of the effect of S-atom doping on the optoelectronic properties of stanene.

Based on the first principles, the influence of S-atom doping on the electronic and optical properties of stanene is comprehensively examined in this work. The results show that pure stanene is a quasi-metal with zero bandgap. After doping with an S atom, opening the bandgap of pure stanene becomes possible and the state of the stanene is converted from quasi-metal to semiconductor. Analysis of the density of states reveals that the density of states of all doped systems is primarily made of the p-orbital of the Sn. The overlap population analysis showed that charge transfer occurs between S and Sn atoms under different doping concentrations. The charge transfer increases with increasing doping concentration. The charge transfer reaches a maximum at a doping concentration of 9.38%. The increase in doping concentration causes blue-shifting of the absorption and reflection peaks of the doped system as compared to those of pure stanene. It is expected that these studies can provide theoretical guidance for the practical application of stanene in optoelectronic devices. All simulations are undertaken with the Cambridge Sequential Total Energy Package (CASTEP) (Wei et al. Physica B: Condensed Matter 545:99, 2018; Bafekry et al. Phys Chem Chem Phys, 2021; Zala et al. Appl Surf Sci, 2022; Bafekry et al. Nanotechnology, 2021; Bafekry et al. Phys Chem Chem Phys, 2021; Bafekry et al. J Phys: Condens Matter, 2021), which is based on density functional theory (DFT). For the exchange correlation, the generalized gradient approximation (GGA) is implemented with the Perdew-Burke-Ernzerhof (PBE) functional Perdew et al. Phys Rev B Condens Matter 48:4978, 1993. Using the Monkhorst-Pack technique, a specific K-point sample of the Brillouin zone was carried out Monkhorst and Pack Phys Rev B 13:5188, 1976. After the convergence tests, the K-point grid was set to 3 × 3 × 1. The plane-wave truncation energy was set to 400eV. The residual stress for all atoms was 0.03eV/Å. The energy convergence criterion was 1.0 × 10-5eV. To prevent recurring interactions between the layers, a vacuum layer with a thickness of 20Å was established in the Z-direction.

Theoretical study of a Ti4 cluster interacting with B-doped and non-doped multivacancy graphene

A density functional theory study was performed to understand the interactions of a small Ti4 cluster with multi-vacancy graphene. We also consider the effect produced by the B-doping of the vacancy defect. In this sense, we analyze the binding mechanisms of the metal cluster. The focus is set on its stability on the substrate, geometrical structure and the interactions participating between the cluster and graphene substrate. A qualitative study of the principal bonds was carried out employing overlap population and bond order chemical descriptors. Additionally, as an attempt to comprehend better the electronic structure and related properties, we performed total density of states, band structure and magnetic moment calculations to characterize the electrical and magnetic properties of the B-doped and non-doped systems.

Spectroscopic, computational, cytotoxicity, and docking studies of 6-bromobenzimidazole as anti-breast cancer agent.

6-Bromobenzimidazole (6BBZ) has been calculated in this study utilizing the 6-311++G(d,p) basis set and the Becke-3-Lee-Yang-Parr density functional approaches. The basic frequencies and geometric optimization are known. FTIR, FT-Raman, and UV-Vis spectra of the substance are compared between its computed and observed values. The energy gap between highest occupied molecular orbital-lowest unoccupied molecular orbital and molecule electrostatic potentials has been represented by charge density distributions that may be associated with the biological response. Time-dependent density functional theory calculations in the gas phase and dimethyl sulfoxide were carried out to ascertain the electronic properties and energy gap values using the same basis set. Molecular orbital contributions are investigated using the overlap population, partial, and total densities of states. Natural bond analysis was found to have strong electron delocalization by means of π(C4-C9) → π*(C5-C6), LP (N1) → π*(C7-C8), and LP(Br12) → π*(C5-C6) interactions. The Fukui function and Mulliken analysis have been explored on the atomic charges of the molecule. The nuclear magnetic resonance chemical shifts for 1 H and 13 C have been computed using the gauge-independent atomic orbital technique. With the highest binding affinity (-6.2 kcal mol-1 ) against estrogen sulfotransferase receptor (PDB ID: 1AQU) and low IC50 value of 17.23 μg/mL, 6BBZ demonstrated potent action against the MCF-7 breast cancer cell line. Studies on the antibacterial activity and ADMET prediction of the molecule have also been carried out.

Simple and robust estimation of average treatment effects for the overlap population using model averaging

The propensity score plays a central role in estimating causal effects in observational studies. Recently, considerable research has been conducted on specific causal estimands that represent the target population for causal effect estimation. In this manuscript, our focus is on the average treatment effects for the overlap population (ATO), where the estimand relies on the ‘true’ propensity score. Consequently, any misspecification of the propensity score model can introduce significant bias to the estimation of the causal effect. To address this issue, we present a novel approach for estimating propensity scores using a model-averaging method that ensures more robust causal effect estimators than a single propensity score model even with the misspecification of some propensity score models. The proposed procedure is user-friendly, as it only involves the use of generalized linear models in freely available software packages, such as ‘glm’ in R and the ‘GENMOD’ procedure in SAS, among others. Also, we propose a novel augmented inverse probability weighting estimator for the ATO that has boundedness; the estimator has the same support as the interested outcome. Through extensive simulation and real data analysis, we demonstrated that the proposed method yields stable and efficient causal estimators for the ATO estimand.

How to perform prespecified subgroup analyses when using propensity score methods in the case of imbalanced subgroups

BackgroundLooking for treatment-by-subset interaction on a right-censored outcome based on observational data using propensity-score (PS) modeling is of interest. However, there are still issues regarding its implementation, notably when the subsets are very imbalanced in terms of prognostic features and treatment prevalence.MethodsWe conducted a simulation study to compare two main PS estimation strategies, performed either once on the whole sample (“across subset”) or in each subset separately (“within subsets”). Several PS models and estimands are also investigated. We then illustrated those approaches on the motivating example, namely, evaluating the benefits of facial nerve resection in patients with parotid cancer in contact with the nerve, according to pretreatment facial palsy.ResultsOur simulation study demonstrated that both strategies provide close results in terms of bias and variance of the estimated treatment effect, with a slight advantage for the “across subsets” strategy in very small samples, provided that interaction terms between the subset variable and other covariates influencing the choice of treatment are incorporated. PS matching without replacement resulted in biased estimates and should be avoided in the case of very imbalanced subsets.ConclusionsWhen assessing heterogeneity in the treatment effect in small samples, the “across subsets” strategy of PS estimation is preferred. Then, either a PS matching with replacement or a weighting method must be used to estimate the average treatment effect in the treated or in the overlap population. In contrast, PS matching without replacement should be avoided in this setting.

The mechanical properties and electronic structures of V, Cr, Mn, Fe, Ni atoms doped MoCoB by first‐principles calculation

AbstractMoCoB‐based cermets have been regarded as the potential substitution of WC cermets with high hardness, high melting point and high oxidation resistance. Ternary borides‐based cermets are widely used in extreme environment, such as high‐pressure environment. Therefore, it is significant to explore the mechanical properties and electronic structures of transition elements X (X = V, Mn, Fe, Ni) atoms doped MoCoB under high pressure, which are performed by first‐principles calculations to provide guidance for industry applications. The analysis of cohesive energy and formation enthalpy indicates high pressure leads to unstable states with lower lattice constants and crystal volumes. The deviation of cohesive energy and formation enthalpy indicate Mo4Co3FeB4 and Mo4Co3NiB4 have similar stability. The shear modulus, Young's modulus and bulk modulus increase under high pressure, which consists with the increasing of covalence. The variation of ductility and anisotropy indicate similar upward trend, which is verified by Poisson's ratio, B/G ratio and anisotropy index AU. The analysis of overlap population indicates high pressure leads to the increasing of covalence of B‐Co covalent bonds and the decreasing of the covalence of B‐Mo covalent bonds. The analysis of electronic structures indicates the high pressure leads to higher hybridization and lower density of states of metallic bonds. The analysis of charge density difference consists with the variation of mechanical properties, implying shorter bond length and higher bonds strength under high pressure.

Surface hydration of zircon and its influence on the adsorption of typical flotation collectors: First-principle calculations

Zirconium and hafnium are critical metals mainly extracted from the zircon mineral. However, due to the unclear surface properties of zircon, most designed flotation collectors (Surfactants to selectively enhance the hydrophobicity of targeted materials) cannot recover zircon effectively. Herein, zircon surface hydration microstructures and their effects on the adsorption of typical flotation collectors (i.e., phosphates, hydroxamic acids, carboxylic acids) have been revealed by systematic first-principles calculations. The speciation diagram and the surface hydration microstructures of zircon have shown that surface Zr sites with small coordination numbers have stronger water affinity. Water molecules have affected the final stable adsorption configurations of the collector. The further obtained adsorption energy of collectors shows that water molecules have weakened the activity of zircon surfaces and reduced the interaction intensity between collectors and surfaces. These results indicate that collectors with stronger negative charges and a lower highest occupied molecular orbital (HOMO) energy can tightly bind with the zircon surface. The electron localization function, density of states, and crystal orbital overlap population have consistently shown that collectors have formed ionic bonds with surface Zr sites. These conclusions should be meaningful for further design of flotation collectors to realize selective zircon flotation.

Chemical Bonding in Large Systems Using Projected Population Analysis from Real-Space Density Functional Theory Calculations.

We present an efficient and scalable computational approach for conducting projected population analysis from real-space finite-element (FE)-based Kohn-Sham density functional theory calculations (DFT-FE). This work provides an important direction toward extracting chemical bonding information from large-scale DFT calculations on materials systems involving thousands of atoms while accommodating periodic, semiperiodic, or fully nonperiodic boundary conditions. Toward this, we derive the relevant mathematical expressions and develop efficient numerical implementation procedures that are scalable on multinode CPU architectures to compute the projected overlap and Hamilton populations. The population analysis is accomplished by projecting either the self-consistently converged FE discretized Kohn-Sham orbitals or the FE discretized Hamiltonian onto a subspace spanned by a localized atom-centered basis set. The proposed methods are implemented in a unified framework within the DFT-FE code where the ground-state DFT calculations and the population analysis are performed on the same FE grid. We further benchmark the accuracy and performance of this approach on representative material systems involving periodic and nonperiodic DFT calculations with LOBSTER, a widely used projected population analysis code. Finally, we discuss a case study demonstrating the advantages of our scalable approach to extract the quantitative chemical bonding information of hydrogen chemisorbed in large silicon nanoparticles alloyed with carbon, a candidate material for hydrogen storage.

Vliyanie primesey na adsorbtsiyu kisloroda na poverkhnosti Ti5Si3(0001)

The influence of simple and transition metal impurities, as well as interstitial impurities (B, C, and N), on the oxygen adsorption on the Ti5Si3 titanium silicide surface has been studied using the of projector augmented wave method within the electron density functional theory. It has been shown that titanium-substituting impurities belonging to the latter halves of the 3d–5d periods cause most significant changes in the adsorption energy. In addition, simple metals and interstitial impurities reduce the oxygen–surface interaction. By analyzing local electron densities of states, charge density difference distribution, charge transfer, and the overlap population of oxygen bonds to nearest-neighbor atoms, we have revealed special aspects of impurity influence on chemical bonding between the titanium silicide surface and oxygen. Factors responsible for an increase/decrease in the adsorption energy of oxygen on the doped surface are discussed. A correlation between the change in adsorption energy and the electronegativity of impurities has been found.

Effect of the hydration film on the surface sulfidization of different oxide ores: A DFT study

Sulfidization is a commonly used pretreatment process to improve the flotation of oxide ores. However, not all oxide minerals can be sulfidized. The huge sulfidization differences between smithsonite and quartz are a typical example. In this paper, DFT calculations were used to simulate the sulfidization of different oxide ores with smithsonite and quartz as an example. The calculation results showed that the hydration film plays a decisive role in whether the oxide ore can be sulfidized or not. For the smithsonite, HS can break the barrier of its surface hydration film and it can be sulfidized. However, for the quartz, due to the powerful obstacle of its surface hydration film to HS, its sulfidization failed. To find out the internal mechanism, the overlap population, PDOS, and electronic configurations were further analyzed, and their relationship with sulfidization behaviors was established. The analysis results demonstrated that Zn-O bond was more vulnerable than Zn-S bond while Si-O was much more intense than Si-S bond. Moreover, a mechanism model was also proposed to elucidate the different impacts of hydration film on the sulfidization of these two representative minerals. This work is helpful to enhance the understanding of different oxide ore sulfidization.

DFT study of superlight ambient temperature reversible H2 storage media based on Li decorated on new planar BCN

A novel 2D pm-BCN monolayer with unique porous geometry, superlight mass, and superior stability is a promising candidate for hydrogen storage. However, pure 2D materials suffer from the weak Van de Waals interaction between the H2, and modification becomes necessary to improve their performance. Here, we design a new complex by decorating active Li ions on the 2D pm-BCN substrate. The decoration of Li can transfer a partial electron to the substrate pm-BCN, which enhances the original π bonding among pm-BCN and induce more active sites on it. Both Li and BCN can act as the adsorption sites. The H2 can realize reversible adsorption under an ambient condition with average adsorption energy of −0.20 eV/H2 and a gravimetric capacity of 6.34 wt%, which surpasses the targe value set by U.S. Department of Energy (DOE). Rigorous analysis of its electronic properties, including a partial density of states, charge density, and crystal orbital overlap population, illustrates that the polarization mechanism contributes to the enhancement of the hydrogen storage capacity of Li@pm-BCN.

Strain effect on the high T c superconductor YBa2Cu3O7: an ab initio study comparing bulk and monolayer models

In this work, the effect of strain on the vibrational and electronic properties of the YBa2Cu3O7 compound was studied through ab initio calculations. For this, two structural models were used: a bulk model and a surface model (a monolayer with CuO2 and BaO as the terminating layers). The phonon spectra was calculated for both structures under different levels of c axis strain. The most appreciable change occurs in the vibrational properties, and in the surface case. From the simulation of the Raman spectra, we were able to quantify the Raman shift ratio as a function of the applied strain, and analyzed its behavior in terms of the overlap population of the different bonds and the reduced mass of selected phonons. The effect of the level of deformation on the band structure and the electronic density of states is small for both structures, although more noticeable in the case of the surface model. In both cases, tendencies are observed when the fine features of the band structure are analyzed by means of the tight binding model. Due to the lower symmetry, the surface model also shows modifications of the bands related to the CuO2 planes.

Adjusting OH tolerance of Ni4 clusters supported on ultra-small carbon nanotube with lattice vacancies for hydrogen oxidation catalysts

The hydroxide (OH) binding on Ni4 clusters supported on the (5, 5) ultra-small carbon nanotubes (CNTs) with lattice vacancies is theoretically investigated by applying the density functional theory (DFT) method. All Ni4 clusters are strongly adsorbed on the (5, 5) ultra-small CNTs with lattice vacancies and formed very stable Ni4/Vn structures. The results show that the OH binding energy (OHBE) at a Ni site nearly increases linearly with increasing Ni d band center. On the other side, this OHBE also increases as the number of vacancies increases. These findings could be attributed to interactions with carbon dangling bonds, which alter the electronic structure of the CNT-supported Ni4 clusters. Furthermore, an unusual behavior is observed for a Ni4 cluster supported on the (5, 5) ultra-small without a vacancy, where its OHBE is noticeably stronger than the others. These assertions are also supported by the projected crystal orbital overlap population (pCOOP), the projected crystal overlap Hamiltonian population (pCOHP), and the Mulliken–Löwdin analyses, which confirm the presence of bonding, anti-bonding, and non-bonding of OH states on Ni4/Vn. As a result, we can conclude that OH strongly binds to all Ni4/Vn. Adjusting OHBE tolerance to the Ni4 clusters is regarded as evidence of the CNT support effect, resulting in an increase in the activity of the hydrogen oxidation reaction (HOR) catalyst in an alkaline environment. It is necessary to make the high performance of the Ni cluster catalysts.

Long-term survival of female versus male patients after coronary artery bypass grafting

Several of the most extensively used risk prediction tools for coronary artery bypass grafting outcomes include female sex as an independent risk factor for postoperative outcomes. It is not clear whether this putative increased surgical risk impacts long-term survival. This study aimed to assess sex differences in 10-year all-cause mortality. Retrospective analysis of 5340 consecutive patients undergoing primary isolated coronary artery bypass surgery, performed from 2000 to 2015, in a Portuguese level III Hospital. The primary endpoint was all-cause mortality at ten years. We employed an overlap weighting algorithm to minimize confounding. Its target population highlights patients with the most overlap in their observed characteristics, and its corresponding estimand is the average treatment effect in the overlap population. We identified that 5340 patients underwent isolated CABG: 1104 (20.7%) were female, and 4236 (79.3%) were male. Sixteen patients were lost to follow-up (0.3%). The median follow-up time was 12.79 (IQR, 9.52-16.66) years: 12.68 (IQR, 9.48-16.54) years for the male patient group and 13.13 (IQR, 9.75-16.98) years for the female patient group. The primary endpoint of all-cause mortality at ten years occurred in 1106 patients (26.1%) in the male patient group, compared with 315 (28.5%) in the female patient group. The unweighted survival analysis for both groups reveals the worst long-term prognosis for the female cohort (hazard ratio, 1.22; 95% CI, 1.10 to 1.35; p < 0.001), while in the overlap weighted survival analysis, such long-term difference in prognosis disappears (hazard ratio, 0.98; 95% CI, 0.88 to 1.09; p = 0.693). In this longitudinal, population-level analysis of patients undergoing primary, isolated CABG, we demonstrated that the female sex is not associated with increased long-term all-cause mortality compared to their male counterparts. Thus, sex should not influence the undertaking of an adequate revascularization strategy.

Regulating anionic redox activity of lithium-rich layered oxides via LiNbO3 integrated modification

Lithium-rich layered oxide cathodes suffer from severe interfacial degradation, capacity attenuation and voltage fading which mainly result from poor reversibility of anionic redox. In this study, a LiNbO3 integrated strategy including LiNbO3 coating, spinel heterostructure and Nb5+ doping has been proposed for stabilizing lattice oxygen and improving structural stability. Among them, the LiNbO3 coating layer can protect highly active peroxo-like oxygen from the electrolyte and spinel heterostructure with three-dimensional (3D) lithium transport channels facilitates the diffusion kinetics. More importantly, Nb5+ dopants inserting into subsurface lattice regulate localized electron configuration and strengthen the reversibility of anionic redox. Theoretical calculation results including density of states and crystal orbital overlap populations unravel the active O-O dimer still coordinates with crystal framework under fully delithiated state after Nb doping exhibiting enhanced anionic redox reversibility and structural stability. Corresponding analysis suggest that doping Nb5+ cations possessing no valence electron (4d0) and low electronegativity could transform Mn-O system into electrochemical inactive Nb-O system with large charge transfer and low d orbital repulsion (Mott-Hubbard regime). Moreover, this inactive Nb-O system cannot provide any reactive electron from Nb5+ cation and oxygen holes have to be isolated on O 2p orbitals, leading to the enhanced reversibility of anionic redox. This integrated modification strategy provides inspiring insights for understanding and regulating the reversibility of anionic redox, showing great potential in designing high-performance lithium-rich Mn-based cathodes.

Structural and bonding properties of small hydrocarbons inside Ca(squarate)-metal organic framework: ab-initio study

Ab−initio Molecular Dynamic (MD) and static Density Functional Theory (DFT) are used to study the structural and bonding properties of small hydrocarbon adsorbates inside Ca(squarate)−Metal Organic Framework (MOF). Car−Parrinello Molecular Dynamics (CPMD) simulations of a single−adsorbate−MOF structure are used to obtain the adsorbate most preferred site of adsorption. This site is used for further structural and bonding analyses using static DFT. Unlike many other MOFs; we found that the Ca(squarate)−MOF physisorbs and weakly binds small adsorbate molecules such as C2H2, C2H4, C2H6, and C3H8 with no observed charge transfer and minimal hybridization with the MOF orbitals. No covalent bonding is seen near the preferred site of adsorption. The calculated binding energies decreases as the H content in the adsorbate molecule increases and found to be −18.71 kJ/mol, −18.14 kJ/mol, −15.75 kJ/mol, and—4.47 kJ/mol for C2H2, C2H4, C2H6, and C3H8 molecules respectively. Density of State (DOS) and a Crystal Orbital Overlap Population (COOP) analyses show that the interactions between C and H atoms in the molecule and C and O atoms in the MOF have antibonding characteristics near the Fermi level. These antibonding states tend to destabilize the overall electronic structure of the combined adsorbate/MOF system and hence decrease the binding energies of these adsorbates inside the MOF.