Energy Minimization Calculations Research Articles

Programmable 2D materials through shape-controlled capillary forces

In recent years, self-assembly has emerged as a powerful tool for fabricating functional materials. Since self-assembly is fundamentally determined by the particle interactions in the system, if we can gain full control over these interactions, it would open the door for creating functional materials by design. In this paper, we exploit capillary interactions between colloidal particles at liquid interfaces to create two-dimensional (2D) materials where particle interactions and self-assembly can be fully programmed using particle shape alone. Specifically, we consider colloidal particles which are polygonal plates with homogeneous surface chemistry and undulating edges as this particle geometry gives us precise and independent control over both short-range hard-core repulsions and longer-range capillary interactions. To illustrate the immense potential provided by our system for programming self-assembly, we use minimum energy calculations and Monte Carlo simulations to show that polygonal plates with different in-plane shapes (hexagons, truncated triangles, triangles, squares) and edge undulations of different multipolar order (hexapolar, octopolar, dodecapolar) can be used to create a rich variety of 2D structures, including hexagonal close-packed, honeycomb, Kagome, and quasicrystal lattices. Since the required particle shapes can be readily fabricated experimentally, we can use our colloidal system to control the entire process chain for materials design, from initial design and fabrication of the building blocks, to final assembly of the emergent 2D material.

Enhanced Computational Study with Experimental Correlation on I-V Characteristics of Tantalum Oxide (TaOx) Memristor Devices in a 1T1R Configuration.

Memristors, non-volatile switching memory platform, has recently attracted significant interest, offering unique potential to enable the realization of human brain-like neuromorphic computing efficiency. Memristors also demonstrate excellent temperature tolerance, long-term durability, and high tunability with nanosecond pulses, making them highly attractive for neuromorphic computing applications. To better understand the material processing, microstructure, and property relationship of switching mechanisms in memristor devices, computational methodologies, and tools are developed to predict the I-V characteristics of memristor devices based on tantalum oxide (TaOx) resistive random-access memory (ReRAM) integrated with an n-channel metal-oxide-semiconductor (NMOS) transistor. A multiphysics model based on coupled partial differential equations for electrical and thermal transport phenomena is solved for the high- and low-resistance states during the formation, growth, and destruction of a conducting filament through SET and RESET stages. These stages effectively represent the migration of oxygen vacancies within an oxide exchange layer. A series of parametric studies and energy minimization calculations are conducted to determine probable ranges for key material and model parameters accounting for the experimental data. The computational model successfully predicted the measured I-V curves across various gate voltages applied to the NMOS transistor in the one transistor one resistance (1T1R) configuration.

The effect of oxygen fugacity on the evaporation of boron from aluminoborosilicate melt

Abstract. We present the results of B2O3 evaporation experiments from Ca- and Mg-bearing aluminoborosilicate melts. Our experiments were conducted at 1245 to 1249 ∘C and 1350 to 1361 ∘C for different run times (60–1020 min), and at oxygen fugacities (logfO2) relative to the fayalite–magnetite–quartz (FMQ) buffer of FMQ−6 to FMQ+1.5, and in air. Our results show that with increasing fO2, evaporation of B from the melt increases by a factor of 5 compared to reducing conditions. Using Gibbs free energy minimization calculations, we suggest two possible evaporation reactions for B2O3 which constrain its speciation in the gas phase to be either 3+ or 4+ (B2O3(g) and BO2(g)). The measured B2O3 contents of the B evaporated residual glasses were used to calculate evaporation rate constants (ki) for B2O3 in oxidizing conditions (air, ki=2.09×10-4 cm min−1 at 1350 ∘C) and reducing conditions (FMQ−4, ki=4.46×10-5 cm min−1 at 1350 ∘C). The absence of diffusion profiles in the experimental glasses suggests that the evaporation rates are slower than B2O3 diffusion rates and therefore the rate-limiting process. Overall, the rate of B evaporation in air is approximately a factor of 5 higher compared to reducing conditions at FMQ−4.

Comprehensive quantum chemical study of the associative complex of para-aminobenzoic acid and 7-diethylamino 4-methyl coumarin by adsorption and aromatic bridges.

The present study accounts for the quantum chemical and nonlinear optical properties of the combination of para-aminobenzoic acid and 7-diethylamino 4-methyl coumarin. Three different complexes were designed, surface interaction (adsorption) and two by connecting both molecules with π-bridge benzene and biphenyl. The amino and carboxyl groups were observed to behave as strong donor and acceptor sites in all the complexes. The band gap of the adsorbed complex was found more suitable. The absorption wavelength and intensity both were seen to increase with the increase in the number of benzene rings in the π-bridge. The values of first- and second-order hyperpolarizability suggest the improved nonlinear optical responses of the introduced complexes. Additionally, the negative value of second-order hyperpolarizability suggests the possibility of the occurrence of reverse saturable absorption in these combinations. The reported work gives theoretical insights into the nonlinear optical properties of the combination of para-aminobenzoic acid and 7-diethylamino 4-methyl coumarin. The molecular modeling and the quantum chemical studies were performed with Gaussian software packages. The standard B3LYP-6-311++G(d,p) basis functionals were used for energy minimization and other spectral calculations. All the surface analyses reported here are obtained by employing Multiwfn software. The chemical reactivity was established by the global reactivity descriptors. The intramolecular interactions and charge localization were stated using inter-fragment charge transfer analysis.

Additional PfCRT mutations driven by selective pressure for improved fitness can result in the loss of piperaquine resistance and altered Plasmodium falciparum physiology.

Our study leverages gene editing techniques in Plasmodium falciparum asexual blood stage parasites to profile novel mutations in mutant PfCRT, an important mediator of piperaquine resistance, which developed in Southeast Asian field isolates or in parasites cultured for long periods of time. We provide evidence that increased parasite fitness of these lines is the primary driver for the emergence of these PfCRT variants. These mutations differentially impact parasite susceptibility to piperaquine and chloroquine, highlighting the multifaceted effects of single point mutations in this transporter. Molecular features of drug resistance and parasite physiology were examined in depth using proteoliposome-based drug uptake studies and peptidomics, respectively. Energy minimization calculations, showing how these novel mutations might impact the PfCRT structure, suggested a small but significant effect on drug interactions. This study reveals the subtle interplay between antimalarial resistance, parasite fitness, PfCRT structure, and intracellular peptide availability in PfCRT-mediated parasite responses to changing drug selective pressures.

Computational verification of conductive Be2Zn monolayer as a superior anode for alkali and alkaline ion batteries

Availability of high-performance anode materials remains a great challenge for the clean energy storage systems. Here, we predict the planar hexacoordinate Be2Zn monolayer by first-principles calculations as a highly conductive metallic conductor with all-round structural stabilities. More impressively, the material delivers ultrahigh theoretical specific capacities of 1285, 1928, 1285, and 3856 mA h g−1 for Li, Na, K, and Ca atoms, respectively, with low migration barriers of 18, 7, 4, and 119 meV as well as with favorite average open-circuit voltages of 0.346, 0.366, 0.322, and 0.151 V. Its structural reversibility at the maximum loading concentrations is jointly confirmed by ab-initio molecular dynamics simulations at the upper temperature of 400 K for commercial battery operation under normal ambient environments and subsequent energy minimization calculations. Moreover, the monolayer can tolerate heavy tensile strain up to around 20% far surpassing the structural deformations at different charging stages, which convincingly guarantees its superlative cycle stability during the charging and discharging processes. Taken together, these appealing findings show that the metallic Be2Zn monolayer has great potential to be used as a universal Li, Na, K, and Ca ion battery anode.

Structural, Elastic and Mechanical Properties of Cubic Perovskite Materials

In this manuscript, theoretical work has been done on series of cubic perovskites RbVF3, RbMnF3, RbFeF3, RbCoF3, RbNiF3, RbCuF3, and RbZnF3. The main focus is on to compute structural, elastic and mechanical properties of cubic materials. All subjected computational results are collected by using Linearized Augmented Plane Wave (FP-LAPW) method using Density Function Theory (DFT). The calculated structural parameters including initial geometry optimization, energy minimization calculations, and total energy values reasonably agree with the previous work. The elastic properties contain C11 (for length), C12 (for volume) and C44 (for shape). These constants are used for calculations of different parameters to discuss mechanical properties. The results show that series of RbMF3 (V, Mn, Fe, Co, Ni, Cu and Zn) contains metallic bonding and anisotropic behavior. The temperature increases from RbVF3 to RbZnF3.These materials are ductile by nature. However, among all materials, RbZnF3 is the hardest material and also contains highest melting temperature. Hence by calculating these useful elasto-mechanical results they can be applicable in various devices for technological benefits so the current investigation signifies that these calculations provide a baseline for new researchers to establish further work.

Multilamellar spherical micelles of alkali lignin: dissipative particle dynamics simulations.

Lignin has an immense potential for the production of lignin-based functional materials. In this work, effect of 2-chloro-ethyltrimethyl ammonium chloride (AC)-grafted alkali lignin (AL) on the morphologies in water was investigated by dissipative particle dynamics (DPD) simulations. The results showed that AL molecules formed spherical micelles, but the corresponding phenylpropane units of AL were randomly distributed in spherical micelles. However, AC-grafted modification of phenolic hydroxyl groups in AL led to the formation of multilamellar spherical micelles. The formation of multilamellar spherical micelles of AL mainly went through four stages: small clusters, larger aggregates with a core-shell structure, trilaminar, and multilamellar spherical micelles. AL molecules resulted in dimethomorph molecules being randomly distributed in the spherical micelle, while the dimethomorph molecules were perfectly entrapped into the spherical micelles of AC-grafted AL. Various molecular weights of AL had no effect on the formation and size of multilamellar spherical micelles. With increasing the content of AC-grafted AL, small clusters, multilamellar spherical micelles, tube-like, and lamellar aggregates were observed successively. This work highlights the potential of lignin to prepare monodispersed lignin-based functional colloidal spheres. Coarse-grained beads were performed energy minimization, geometric optimization, NPT ensemble (298 K and 1.0 bar), and NVT ensemble (298 K) calculations. DPD simulations were carried out at 300,000 steps in a 30×30×30 Rc3 cubic box with Materials Studio 7.0 program.

Tellurium isotope fractionation during evaporation from silicate melts

As a moderately volatile, redox-sensitive chalcophile and siderophile element, Te and its isotopic composition can inform on a multitude of geochemical and cosmochemical processes. However, the interpretation of Te data from natural settings is often hindered by an insufficient understanding of the behavior of Te in high-temperature conditions. Here, we present the results of Te evaporation and isotopic fractionation in silicate melting experiments. The starting material was boron-bearing anorthite-diopside glass with 1 wt% TeO2. The experiments were conducted over the temperature range of 868–1459 °C for 15 min each, and at oxygen fugacities (logfO2) relative to the fayalite-magnetite-quartz buffer (FMQ) of FMQ−6 to FMQ+1.5, and in air. Evaporation of Te decreases with decreasing fO2. For high-temperature experiments performed at >1200 °C Te loss is accompanied by Te isotope fractionation towards heavier compositions in the residual glasses. By contrast, Te loss in experiments performed at temperatures <1200 °C typically resulted in lighter Te isotopic compositions in the residues relative to the starting material. In air, Te evaporates as TeO2, whereas at lower oxygen fugacities we predict the evaporation of Te2, using Gibbs free energy minimization calculations. In air, the experimentally determined kinetic isotopic fractionation factor for δ128/126Te at T > 1200 °C is αK = 0.99993. At reducing conditions, Te likely substitutes as Te2− for O2– in the melt structure and becomes increasingly soluble at highly reducing conditions. Consequently, Te evaporation is not predicted for volcanic processes on reduced planetary bodies such as the Moon or Mercury.

Effect of hydrostatic pressure on structural and opto-electronic properties for barium based oxide perovskite

In this study, the effects of hydrostatic pressure ranges from 0 Gpa to 20 Gpa on detailed pressure induced computations of Barium Zirconate BaZrO3, including initial geometry optimization, energy minimization calculations, total energy values, lattice parameters, energy band gaps (Eg), optical and elastic constants are reported. All subjected computational results are collected by applying Local Density Approximation functional proposed by Ceperley-Alder and reformulated by Perdew-Zunger (LDA-CAPZ) using Cambridge Serial Total Energy Package (CASTEP) module under the formulation of Density Function Theory (DFT). The reduced nature of cell volume as well as lattice constants confirm the structural compressibility of BaZrO3 under the application of applied pressure. Increasing bulk modulus values indicate maximum structural stiffness of BaZrO3 under applied pressure. The collected values are compared with available theoretical and experimental parameters. The investigated band structures predict direct bandgap of BaZrO3, that increase under the influence of applied pressure which tend to increase all optoelectronic behavior. So, the current investigation signifies, that these calculations provide a baseline for new researchers to establish further pressure investigations and could be helpful for the uses of BaZrO3 in optoelectronic applications.

Global instability index as a crystallographic stability descriptor of halide and chalcogenide perovskites

Crystallographic stability is an important factor that affects the stability of perovskites. The stability dictates the commercial applications of lead-based organometal halide perovskites. The tolerance factor (t) and octahedral factor (μ) form the state-of-the-art criteria used to evaluate the perovskite crystallographic stability. We studied the crystallographic stabilities of halide and chalcogenide perovskites by exploring an effective alternative descriptor, the global instability index (GII) that was used as an indicator of the stability of perovskite oxides. We particularly focused on determining crystallographic reliability by calculating GII. We analyzed the bond valence models of the 243 halide and chalcogenide perovskites that occupied the lowest-energy cubic-phase structures determined by conducting the first-principles-based total energy minimization calculations. The decomposition energy (ΔHD) reflects the thermodynamic stability of the system and is considered as the benchmark that helps assess the effectiveness of GII in evaluating the crystallographic stability of the systems under study. The results indicated that the accuracy of predicting thermodynamic stability was significantly higher when GII (73.6%) was analyzed compared to the cases when t (55%) and μ (39.1%) were analyzed to determine the stability. The results obtained from the machine learning-based data mining method further indicate that GII is an important descriptor of the stability of the perovskite family.

Supramolecular gating of guest release from cucurbit[7]uril using de novo design

Herein we computationally explore the modulation of the release kinetics of an encapsulated guest molecule from the cucurbit[7]uril (CB7) cavity by ligands binding to the host portal. We uncovered a correlation between the ligand-binding affinity with CB7 and the guest residence time, allowing us to rapidly predict the release kinetics through straightforward energy minimization calculations. These high-throughput predictions in turn enable a Monte-Carlo Tree Search (MCTS) to de novo design a series of cap-shaped ligand molecules with large binding affinities and boosting guest residence times by up to 7 orders of magnitude. Notably, halogenated aromatic compounds emerge as top-ranking ligands. Detailed modeling suggests the presence of halogen-bonding between the ligands and the CB7 portal. Meanwhile, the binding of top-ranked ligands is supported by 1H NMR and 2D DOSY-NMR. Our findings open up possibilities in gating of molecular transport through a nanoscale cavity with potential applications in nanopore technology and controlled drug release.

Raman spectra of carbon nanowires made of single walled carbon nanotubes encasing polyynes

In this work, the Raman spectra of LCCs encapsulated single-walled carbon nanotubes (SWCNTs) are calculated using the spectral moment’s method. To derive the optimum configurations of the linear carbon chains inside nanotubes, the minimum energy calculations using a convenient Lennard-Jones expression of the van der Waals intermolecular potential is devoted. The optimized structures show that the minima correspond to nanotubes configurations with diameter close to 0.68nm. The influence of the nanotube diameter and chirality are investigated. We also address the important question of the effect of filling degree using the frequency of Raman active modes. These predictions are useful to interpret the experimental data.

Interfacial self-assembly of SiO2-PNIPAM core-shell particles with varied crosslinking density.

Spherical particles confined to liquid interfaces generally self-assemble into hexagonal patterns. It was theoretically predicted by Jagla two decades ago that such particles interacting via a soft repulsive potential are able to form complex, anisotropic assembly phases. Depending on the shape and range of the potential, the predicted minimum energy configurations include chains, rhomboid and square phases. We recently demonstrated that deformable core-shell particles consisting of a hard silica core and a soft poly(N-isopropylacrylamide) shell adsorbed at an air/water interface can form chain phases if the crosslinker is primarily incorporated around the silica core. Here, we systematically investigate the interfacial self-assembly behavior of such SiO2-PNIPAM core-shell particles as a function of crosslinker content and core size. We observe chain networks predominantly at low crosslinking densities and smaller core sizes, whereas higher crosslinking densities lead to the formation of rhomboid packing. We correlate these results with the interfacial morphologies of the different particle systems, where the ability to expand at the interface and form a thin corona at the periphery depends on the degree of crosslinking close to the core. We perform minimum energy calculations based on Jagla-type pair potentials with different shapes of the soft repulsive shoulder. We compare the theoretical phase diagram with experimental findings to infer to which extent the interfacial interactions of the experimental system may be captured by Jagla pair-wise interaction potentials.

Defined core–shell particles as the key to complex interfacial self-assembly

The two-dimensional self-assembly of colloidal particles serves as a model system for fundamental studies of structure formation and as a powerful tool to fabricate functional materials and surfaces. However, the prevalence of hexagonal symmetries in such self-assembling systems limits its structural versatility. More than two decades ago, Jagla demonstrated that core-shell particles with two interaction length scales can form complex, nonhexagonal minimum energy configurations. Based on such Jagla potentials, a wide variety of phases including cluster lattices, chains, and quasicrystals have been theoretically discovered. Despite the elegance of this approach, its experimental realization has remained largely elusive. Here, we capitalize on the distinct interfacial morphology of soft particles to design two-dimensional assemblies with structural complexity. We find that core-shell particles consisting of a silica core surface functionalized with a noncrosslinked polymer shell efficiently spread at a liquid interface to form a two-dimensional polymer corona surrounding the core. We controllably grow such shells by iniferter-type controlled radical polymerization. Upon interfacial compression, the resulting core-shell particles arrange in well-defined dimer, trimer, and tetramer lattices before transitioning into complex chain and cluster phases. The experimental phase behavior is accurately reproduced by Monte Carlo simulations and minimum energy calculations, suggesting that the interfacial assembly interacts via a pairwise-additive Jagla-type potential. By comparing theory, simulation, and experiment, we narrow the Jagla g-parameter of the system to between 0.9 and 2. The possibility to control the interaction potential via the interfacial morphology provides a framework to realize structural features with unprecedented complexity from a simple, one-component system.

Identification of SNPs in hMSH3/MSH6 interaction domain affecting the structure and function of MSH2 protein.

MutS homolog 2 (MSH2) is a mismatch repair gene that plays a critical role in DNA repair pathways, and its mutations are associated with different cancers. The present study aimed to find out the single nucleotide polymorphisms (SNPs) of MSH2 protein associated with causing structural and functional changes leading to the development of cancer with the help of computational tools. Four different tools for predicting deleterious SNPs (SIFT, PROVEAN, PANTHER, and PolyPhen), two tools each for identifying disease association (PhD-SNP and SNP&GO) and estimating stability (I-mutant and MUPro) were employed. Homology modeling, energy minimization, and root mean square deviation calculation were used to estimate structural variations. Twenty-seven SNPs and five SNPs (double amino acid change) were identified based on a consensus approach that might be associated with the structural and functional change in MSH2 protein. Molecular docking reveals that six SNPs affect the interaction of MSH2 and MSH6. Twelve identified SNPs were reported to be linked with hereditary nonpolyposis, colorectal cancer, and Lynch syndrome. Further, selected SNPs need to be validated in an in vitro system for their precise association with cancer predisposition.

Surface co-silanization engineering to enhance amine functionality for adhesive heterojunction and antimicrobial application

Surface functionalization of quartz is of practical importance for versatile applications. Amine functionality is constructed on quartz via surface composite engineering with an amine-terminated organosilane, 3-aminopropyl trimethoxysilane (APTMS). In this study, we demonstrate a facile co-silanization method which bulky triphenylsilanol (TPS) is introduced to spatially confine the grafting orientation of functional APTMS, giving rise to a well-organized APTMS-TPS composite nanolayer to maximize amine functionality and suppress molecular agglomeration. Contact angle measurement, atomic force microscopy, angle-resolved X-ray photoelectron spectroscopy, Kelvin probe force microscopy, ultraviolet photoelectron spectroscopy, and energy minimization calculation are used to identify the well-organized conformations of surface co-silanization. The co-silanized APTMS-TPS composite nanolayer exhibits high efficacy in the metal immobilization, acting as an adhesion promoter to increase the adhesion strength of Ni/quartz heterojunction. Immobilization of Ag nanoparticles on amine-functionalized quartz is also achieved which is a facile method to prepare an efficient antimicrobial surface.

Crystal Structure of a Peculiar Polycyclic Aromatic Hydrocarbon Determined by 3D Electron Diffraction

Recently, 7,16-di-tert-butyl-5,14-bis(4-(tert-butyl)phenyl)dibenzo[a,m]rubicene has been reported as a polycyclic aromatic hydrocarbon synthesized through a peculiar Scholl reaction and exhibited promising properties for optical and electronic applications. This compound has been previously crystallized as a solvate, but the presence of disordered solvent molecules has hampered a complete elucidation of its crystal structure. Here we present a novel solvent-free crystal phase of the molecule solved ab initio by 3D electron diffraction (3D ED) from micrometric single crystals. The kinematically and dynamically refined structure has been further corroborated by powder X-ray diffraction and energy minimization calculations, confirming the accuracy of the results achieved by 3D ED. This work discusses the relevance of the crystal structure obtained for possible technological applications and demonstrates the overall significance of 3D ED for the structural determination of challenging small molecules.

Organosiloxane nanolayer as diffusion barrier for Cu metallization on Si

Development of emerging technologies such as artificial intelligence, big data, and smart vehicles brings increasing demands on high-performance integrated circuits (ICs). To achieve this goal, ultra-miniaturization of Cu interconnects as well as diffusion barrier layer to increase the integration density is imperative. In this study, we demonstrate that an ultrathin organosiloxane nanolayer exhibits excellent barrier efficacy against the active diffusion of Cu towards Si. The organosiloxane nanolayer is constructed on the SiO2 surface using dehydration to covalently tether the hydrolyzed organosilane molecules. The amine termini of organosilanes are used to adsorb catalytic Pd nanocluster to accomplish the Cu metallization on Si. Rapid thermal annealing is performed with respect to the Si/SiO2/organosiloxane/Cu junctions to evaluate the efficacy of diffusion barrier. Based on microstructural and crystallographic examinations, the organosiloxane nanolayer with a shorter alkyl chain performs better with a higher breakdown temperature of 923 K at which the Cu diffusion and the Cu silicide formation at the junctions occur. The grafting conformations of organosilane molecules with various alkyl chain lengths on the SiO2 surface are constructed based on energy minimization calculations to rationalize the diffusion barrier efficacy.

Mechanism of Guanosine Triphosphate Hydrolysis by the Visual Proteins Arl3-RP2: Free Energy Reaction Profiles Computed with Ab Initio Type QM/MM Potentials.

We report the results of calculations of the Gibbs energy profiles of the guanosine triphosphate (GTP) hydrolysis by the Arl3-RP2 protein complex using molecular dynamics (MD) simulations with ab initio type QM/MM potentials. The chemical reaction of GTP hydrolysis to guanosine diphosphate (GDP) and inorganic phosphate (Pi) is catalyzed by GTPases, the enzymes, which are responsible for signal transduction in live cells. A small GTPase Arl3, catalyzing the GTP → GDP reaction in complex with the activating protein RP2, constitute an essential part of the human vision cycle. To simulate the reaction mechanism, a model system is constructed by motifs of the crystal structure of the Arl3-RP2 complexed with a substrate analog. After selection of reaction coordinates, energy profiles for elementary steps along the reaction pathway GTP + H2O → GDP + Pi are computed using the umbrella sampling and umbrella integration procedures. QM/MM MD calculations are carried out, interfacing the molecular dynamics program NAMD and the quantum chemistry program TeraChem. Ab initio type QM(DFT)/MM potentials are computed with atom-centered basis sets 6-31G** and two hybrid functionals (PBE0-D3 and ωB97x-D3) of the density functional theory, describing a large QM subsystem. Results of these simulations of the reaction mechanism are compared to those obtained with QM/MM calculations on the potential energy surface using a similar description of the QM part. We find that both approaches, QM/MM and QM/MM MD, support the mechanism of GTP hydrolysis by GTPases, according to which the catalytic glutamine side chain (Gln71, in this system) actively participates in the reaction. Both approaches distinguish two parts of the reaction: the cleavage of the phosphorus-oxygen bond in GTP coupled with the formation of Pi, and the enzyme regeneration. Newly performed QM/MM MD simulations confirmed the profile predicted in the QM/MM minimum energy calculations, called here the pathway-I, and corrected its relief at the first elementary step from the enzyme–substrate complex. The QM/MM MD simulations also revealed another mechanism at the part of enzyme regeneration leading to pathway-II. Pathway-II is more consistent with the experimental kinetic data of the wild-type complex Arl3-RP2, whereas pathway-I explains the role of the mutation Glu138Gly in RP2 slowing down the hydrolysis rate.