Calculation Of Constants Research Articles

Ab Initio Investigation of the Relativistic Effect in the Physical Properties of Intermetallic Superconductor TlBi2${\rm TlBi}_2$ with AlB2${\rm AlB}_2$‐Type Hexagonal Layer Structure

AbstractIn this work, the role of spin‐orbit coupling (SOC) in the physical properties of is reported. These electronic calculations reveal that the heavy elements Tl and Bi promote strong spin‐orbit coupling, lifting some of the degeneracies at the high‐symmetry points. The presence of SOC causes significant decreases in both elastic constants and elastic moduli, which in turn improve the compatibility of the calculated Debye temperature ( = 80 K) with the recent experimental data of 83 K. Furthermore, our quasi‐static harmonic approximation calculation, like this elastic constant calculation, confirms that taking SOC into account improves agreement with the experiment by decreasing value of Debye temperature from 95 to 85 K. Activating the SOC causes significant modifications in the phonon spectrum and the density of phonon states, as well as in the Eliashberg spectral function. As a result of these modifications, the electron–phonon coupling parameter () increases from 1.178 to 1.259, by . The calculated values of both with and without SOC imply that can be treated as phonon‐mediated superconductor with strong coupling. The SOC‐induced increase in brings the superconducting transition temperature of from 6.076 to 6.211 K, which is almost equal to the recent experimental value of 6.2 K.

Tailoring structural and optical properties of ZnO system through elemental Mn Doping through First-principles calculations

In this study, band structure and optical properties of Manganese (Mn) doped ZnO are investigated adopting first-principles study calculations. It is observed that, by addition of Mn in ZnO crystal, the electrical properties like conductivity and dielectric function of material have been improved. The elastic constants for the elements are also calculated which shows that the element is stable after addition of dopant. The computational study is done on CASTEP and Material Studio. The ZnO system is simulated and atoms of Mn has been added replacing Zn atoms. The properties that studied are band structure and optics including conductivity, reflectivity, dielectric function, absorption and refractive index. Furthermore, this study also includes calculation of Elastic constants, XRD Spectra, Phonon dispersion and Temperature profile of doped ZnO systems. The computational study produced promising results and experimental approach can be adopted to reinforce the outcomes of this study.

A Comprehensive Computational Study on the Thermodynamics and Kinetics of Tetrahydrobiopterin Regeneration Process.

One of the most crucial enzymatic cofactors in the human body is tetrahydrobiopterin, which is acquired through biological synthesis and self-regeneration. During this regenerative process, it undergoes oxidation, deprotonation, further oxidation, and subsequent deprotonation, resulting in the formation of quinonoid-dihydrobiopterin, which then undergoes tautomerization to yield dihydrobiopterin. This study presents the thermodynamic and kinetic properties associated with each stage of the regeneration process using theoretical calculations. The redox potentials for oxidation steps and the pKa values for deprotonation steps are determined employing the Born-Haber cycle and the direct change of free energy in implicit solvent models. The redox metabolites are characterized and confirmed from their calculated absorption spectra using the time-dependent density functional theory method. For the tautomerization steps, an IRC calculation is executed, and rate constants are computed using Eyring's Transition State Theory (TST). The tunnelling probability of the H atom during the tautomerization process is incorporated using Wigner's tunnelling correction in the calculation of the rate constant. Notably, we identify the N3 atom as the most probable deprotonation site for H3B+ and predict its geometry based on our calculations. Furthermore, we elucidate the spectral properties of intermediates involved in the regeneration process, highlighting key electronic transitions responsible for their excitations. Our results indicate that each step of tautomerization occurs along vibrational bending modes. We have observed that these tautomerization processes have high activation energies by optimising transition states. Additionally, considering tunnelling correction can significantly affect the reaction rates associated with these processes. These results provide a comprehensive understanding of the thermodynamics and kinetics of the regeneration process of tetrahydrobiopterin, which will help in the modulation of its biological activity.

Non-local effects on displacement in cylindrical structures

This study investigates the influence of non-local effects on displacement variations in polar coordinates for clamped-clamped cylinders, assuming material properties vary as a power function of the thickness coordinate. The displacement expression is derived from a solved differential equation, with particular attention given to the impact of fixation mode on displacement. The findings underscore the importance of non-local factors in determining structural behavior and stress the necessity of considering fixation mode when computing integration constants. Nonlocal effects denote interactions and influences that extend beyond locally observed conditions or alterations within a specific system. Examining clamped-clamped cylinders, this research delves into displacement variations in polar coordinates while considering the influence of non-local effects, assuming material properties change according to a power function of the thickness coordinate. The derivation of the displacement expression from a solved differential equation forms a key aspect, with a specific focus on how fixation mode affects displacement. The study's outcomes highlight the crucial role of non-local factors in shaping structural behavior and underscore the imperative of accounting for fixation mode when calculating integration constants. Focused on clamped-clamped cylinders, this study explores displacement variations in polar coordinates under the influence of non-local effects, presuming material properties to follow a power function of the thickness coordinate. Utilizing a solved differential equation, the investigation derives the displacement expression and scrutinizes how fixation mode impacts displacement. The results elucidate the pivotal significance of non-local factors in delineating structural behavior and stress the requisite consideration of fixation mode in integration constant calculations.

Ergone Derivatives from the Deep-Sea-Derived Fungus Aspergillus terreus YPGA10 and 25,28-Dihydroxyergone-Induced Apoptosis in Human Colon Cancer SW620 Cells.

Ten new ergone derivatives (1-10) and five known analogues (11-15) were isolated from the deep-sea-derived fungus Aspergillus terreus YPGA10. The structures including the absolute configurations were established by detailed analysis of the NMR spectroscopic data, HRESIMS, ECD calculation, and coupling constant calculation. All the structures are characterized by a highly conjugated 25-hydroxyergosta-4,6,8(14),22-tetraen-3-one nucleus. Structurally, compound 2 bearing a 15-carbonyl group and compounds 5-7 possessing a 15β-OH/OCH3 group are rarely encountered in ergone derivatives. Bioassay results showed that compounds 1 and 11 demonstrated cytotoxic effects on human colon cancer SW620 cells with IC50 values of 8.4 and 3.1 μM, respectively. Notably, both compounds exhibited negligible cytotoxicity on the human normal lung epithelial cell BEAS-2B. Compound 11 was selected for preliminary mechanistic study and was found to inhibit cell proliferation and induce apoptosis in human colon cancer SW620 cells. In addition, compound 1 displayed cytotoxic activity against five human leukemia cell lines with IC50 values ranging from 5.7 to 8.9 μM. Our study demonstrated that compound 11 may serve as a potential candidate for the development of anticolorectal cancer agents.

“É importante que não tome mais comprimidos do que lhe foi indicado”: estratégias linguísticas de desresponsabilização da indústria farmacêutica em folhetos informativos

Legally, pharmaceutical companies are responsible for any damage, injury or harm caused to the user by their products. However, the language present in product warnings (Dumas, 1990; Shuy, 1990; Tiersma, 2002) and in patient information leaflets (PIL) (van der Waarde, 2008; Hagemeyer & Coulthard, 2017) seem to protect manufacturers from possible litigation, transferring responsibility to the consumer or user. Therefore, using both a pragmatic and discoursive analysis approach, we aim to investigate which linguistic strategies in European Portuguese (EP) acquit pharmaceutical companies from holding liability for the users’ actions. The qualitative analysis of a corpus of 20 PIL in EP reveals that the use of passive voice, impersonal constructions, attenuation of directive acts, declarative sentences with imperative value and vague language represent intentional strategies for pharmaceutical companies to protect themselves from possible litigation. Additionally, the comprehensibility of the text is further compromised by grammatical inconsistencies, the constant calculation of inferences and the presence of technical terms, “medicalese”.

Reducing Off-State and Leakage Currents by Dielectric Permittivity-Graded Stacked Gate Oxides on Trigate FinFETs: A TCAD Study.

Since its invention in the 1960s, one of the most significant evolutions of metal-oxide semiconductor field effect transistors (MOSFETs) would be the 3D version that makes the semiconducting channel vertically wrapped by conformal gate electrodes, also recognized as FinFET. During recent decades, the width of fin (Wfin) and the neighboring gate oxide width (tox) in FinFETs has shrunk from about 150 nm to a few nanometers. However, both widths seem to have been leveling off in recent years, owing to the limitation of lithography precision. Here, we show that by adapting the Penn model and Maxwell-Garnett mixing formula for a dielectric constant (κ) calculation for nanolaminate structures, FinFETs with two- and three-stage κ-graded stacked combinations of gate dielectrics with SiO2, Si3N4, Al2O3, HfO2, La2O3, and TiO2 perform better against the same structures with their single-layer dielectrics counterparts. Based on this, FinFETs simulated with κ-graded gate oxides achieved an off-state drain current (IOFF) reduced down to 6.45 × 10-15 A for the Al2O3: TiO2 combination and a gate leakage current (IG) reaching down to 2.04 × 10-11 A for the Al2O3: HfO2: La2O3 combination. While our findings push the individual dielectric laminates to the sub 1 nm limit, the effects of dielectric permittivity matching and κ-grading for gate oxides remain to have the potential to shed light on the next generation of nanoelectronics for higher integration and lower power consumption opportunities.

First‐Principles Investigation on the Structural, Mechanical, and Bonding Properties of ZrB2 Under Different Pressures

The crystal structures of zirconium diboride have been thoroughly explored up to 200 GPa by applying the particle‐swarm optimization technique in company with first‐principles calculations. The hexagonal ZrB2 with space group of P6/mmm is always stable in the pressure region of 0–200 GPa. Structurally, this structure consists of the intriguing regular ZrB12 hexagonal column and the planar hexagonal B ring unit. In addition, the stable AlB2–ZrB2 configuration is mechanically and dynamically stable as confirmed by the respective calculations of elastic constants and phonon dispersion curves. The hardness values exhibit a shrinking variation upon further compression, which mainly originates from the decreasing brittleness and degree of the directionality of the covalent bonds with the growing pressure. Interestingly, the analyses of the Poisson's ratio, density of states, electron location function and Bader charge substantiate that a combination of covalent and ionic characters exists in the AlB2–ZrB2 crystalline with the formidable covalent interaction in the BB bonds, and partially covalent and partially ionic interactions in the ZrB bonds. The hardness value for this phase unexpectedly reaches 45.41 GPa under ambient pressure, higher than the lower limit of superhard materials.

On the fate of protonated chloroformates in the gas phase: a competition between forming HCl and chloroformic acid.

Chloroformates are prevalent in the atmosphere due to their utilization as fuel additives and industrial solvents. These species may undergo interactions with atmospheric water resulting in protonated chloroformates. This study delves into the gas-phase dissociation of these protonated species. Tandem mass spectrometry was employed to scrutinize the unimolecular dissociation of protonated methyl (1), ethyl (2), neopentyl (3), and phenyl chloroformate (4). Notably, 1 and 4 exhibited HCl loss, yielding CH3OCO+ and C6H5OCO+, respectively, with 1 additionally generating neutral methanol and ClCO+. 4 additionally loses CO and CO2. In contrast, 2 and 3 each only exhibit a single fragmentation channel, with 2 losing C2H4 to generate protonated chloroformic acid and 3 generating protonated 2-methylbutene by losing neutral chloroformic acid. Density functional theory at the B3LYP/6-311+G(d,p) level of theory was employed to explore minimum energy reaction pathways for each ion, and CBS-QB3 single-point energy calculations were added to provide reliable energetics. The Rice-Ramsperger-Kassel-Marcus (RRKM) calculations of the rate constants for selected competing processes were carried out to link theory and experiment. One common unimolecular process observed was the 1,3-H shift of the proton from the carbonyl oxygen to the ester oxygen before dissociation.

First-principle simulations of inorganic halides Li2TlBiY6 (Y = Cl, Br, I) for optoelectronic applications

In this emerging technological era, lead-free (Li-based) inorganic halides have drawn a lot of researchers’ consideration due to their optoelectronic applications. Based on this, we explored theoretically mechanical, optical, and thermoelectric features of halides Li2TlBiY6 (Y = Cl, Br, I) by employing first-principle simulations (Wien2k code). Our finding of optoelectronic parameters using appropriate mBJ approach is in favorable alignment to previously reported data, and PBEsol is employed to scrutinize structural as well as mechanical features of these materials. The Born stability and formation energy are examined concerning the structural stability associated with all halides. The distinction between brittle and ductile nature is investigated concerning the calculation of elastic constants of the cubic symmetry. Being based on the mBJ potential, the bandgasps for Li2TlBiCl6, Li2TlBiBr6, and Li2TlBiI6 are 2.8 eV, 2.3 eV, and 1.9 eV, correspondingly. To confirm their optimal absorbability in the electromagnetic domain (visible), all halides were further analyzed concerning dielectric parameters. Additionally, thermoelectric properties are explained in detail within the temperature range of 300-800K using classical Boltzmann theory, making them promising materials for thermoelectric applications.

Theoretical Study of Single-Atom Catalysts for Hydrogen Evolution Reaction Based on BiTeBr Monolayer.

Developing an inexpensive and efficient catalyst for a hydrogen evolution reaction (HER) is an effective measure to alleviate the energy crisis. Single-atom catalysts (SACs) based on Janus materials demonstrated promising prospects for the HER. Herein, density functional theory calculations were conducted to systematically investigate the performance of SACs based on the BiTeBr monolayer. Among the one hundred and forty models that were constructed, fourteen SACs with potential HER activity were selected. Significantly, the SAC, in which a single Ru atom is anchored on a BiTeBr monolayer with a Bi vacancy (RuS2/VBi-BiTeBr), exhibits excellent HER activity with an ultra-low |ΔGH*| value. A further investigation revealed that RuS2/VBi-BiTeBr tends to react through the Volmer-Heyrovsky mechanism. An electronic structure analysis provided deeper insights into this phenomenon. This is because the Tafel pathway requires overcoming steric hindrance and disrupting stable electron filling states, making it challenging to proceed. This study finally employed constant potential calculations, which approximate experimental situations. The results indicated that the ΔGH* value at pH = 0 is 0.056 eV for RuS2/VBi-BiTeBr, validating the rationality of the traditional Computational Hydrogen Electrode (CHE) method for performance evaluation in this system. This work provides a reference for the research of new HER catalysts.

Remarkable Optoelectronic Characteristics of Synthesizable Square‐Octagon Haeckelite Structures: Machine Learning Materials Discovery

AbstractThe research explores new compounds with structures similar to square‐octagonal beryllium oxide, commonly known as Haeckelites. The goal is to identify semiconducting variations compounds that can be synthesized and show promising potential in optoelectronic devices. Start with 1083 binary Haeckelite structures, and to test the synthesis potential of these materials quickly, develop new descriptors and use machine learning techniques. As a result, it identifies a subset of 350 materials with suitable properties in terms of phase stability and electronic perspective. These materials are further investigated to analyze their electronic structure and phase stability, which are determined through density functional theory calculations. The phase stabilities of the predicted semiconducting Haeckelites are also compared to other binary compounds using an evolutionary structure search algorithm. The comprehensive methodology also includes examining the dynamic stabilities through phonon calculations and mechanical properties through elastic constant calculations. Eventually, 13 new Haeckelite compounds are discovered, demonstrating exceptional stability and performance in electronic tests. Among these compounds, eight have shown remarkable absorption coefficients and are considered promising candidates with high reflectivity. Additionally, they have exhibited high electron mobility. These findings strongly suggest the potential of these compounds for synthesis and their application in optoelectronic devices.

Restriction on molecular fluxionality by substitution: A case study for the 1,10-dicyanobullvalene.

We show herein that 1,10-dicyano substitution restricts the paragon fluxionality of bullvalene to just 14 isomers which isomerize along a single cycle. The restricted fluxionality of 1,10-dicyanobullvalene (DCB) is investigated by means of: (i) Bonding analyses of the isomer structures using the adaptive natural density partitioning (AdNDP). (ii) Quantum dynamical simulations of the isomerizations along the cyclic intrinsic reaction coordinate of the potential energy surface (PES). The PES possesses 14 equivalent potential wells supporting 14 isomers which are separated by 14 equivalent potential barriers supporting 14 transition states. Accordingly, at low temperatures, DCB appears as a hindered molecular rotor, without any delocalization of the wavefunction in the 14 potential wells, without any nuclear spin isomers, and with completely negligible tunneling. These results are compared and found to differ from those for molecular boron rotors. (iii) Born-Oppenheimer molecular dynamics (BOMD) simulations of thermally activated isomerizations. (iv) Calculations of the rate constants in the frame of transition state theory (TST) with reasonable agreement achieved with the BOMD results. (v) Simulations of the equilibration dynamics using rate equations for the isomerizations with TST rate coefficients. Accordingly, in the long-time limit, isomerizations of the 14 isomers, each with Cs symmetry, approach the "14 Cs → C7v" thermally averaged structure. This is a superposition of the 14 equally populated isomer structures with an overall C7v symmetry. By extrapolation, the results for DCB yield working hypotheses for so far un-explored properties e.g. for the equilibration dynamics of C10H10.

Investigating the Suitability of Various Silver(I) Complexes for Use in a Cyanide-Free Silver Electrolyte

The suitability of various nitrogen, sulfur, oxygen, and phosphorus compounds as complexing agents in a silver electrolyte was examined by using potentiometric titration under practical conditions. The setup consisted of three electrodes to measure the pH and the activity of the silver ions simultaneously. Different ratios of silver to complexing agent from 1:10 to 1:1 at a constant ionic strength of 0.2 mol/L were investigated. The type of the complexes and their corresponding critical stability constants were evaluated by fitting the measured data using a self-developed algorithm. The pH and Nernst potential curve were calculated for the assumed complexes based on the law of mass action to find the best approximation. The correct definition of the occurring species is challenging and can lead to significant changes in the calculation of stability constants. For this reason, the measured silver potential curves were primarily used for the rating of the complexing agents. An evaluation of the measurements shows that the donor atom of the complexing agent and its ligand field strongly affected the stability and type of the complexes. Only a few complexing agents were found to be suitable for use in the cyanide-free silver electrolyte.

Solvatochromism and halochromism in nitro lophine derivatives: Photophysical study, computational calculations and applications as pH sensing material

Nitro Lophines were readily synthesized via multicomponent reaction of benzil, nitro benzaldehyde and ammonium acetate. All three nitro Lophines were isolated in good yields and were also characterized by various analytical and spectroscopic techniques. A distinctive solvatochromism was observed in case of ortho and para nitro containing Lophines in their absorbance spectra. In particular, naked eye solvatochromism was observed, in case of para nitro Lophine, in the form of yellow and red coloured solution in methanol and DMSO respectively. Halochromism studies revealed the hypsochromic shift under acidic pH while bathochromic shift under alkaline pH for both nitro Lophines. Again the para nitro Lophine demonstrated wonderful distinctive colour change under acidic and alkaline pH in both methanol and DMSO as solvents. The measurement of absorbance at different pH values was carried out and the data obtained were used for calculation of dissociation constants employing several graphical methods. Computational calculations were carried out using TD-DFT for UV–Vis absorption calculation while graph-convolutional neural network model was utilized for calculation of dissociation constants. Ultimately, a reusable naked eye pH detection paper could be developed using para nitro Lophine as a sole indicator.

First-principles study of binary and ternary phases in Mg-Gd-Ni alloys

Given the high demand for magnesium alloys across industries, it's crucial to enhance their performance by developing alloys with superior characteristics. The performance of magnesium alloys is closely related to the properties of the precipitated phase. However, there has been insufficient exploration of the mechanical properties of precipitated phases in Mg-Gd-Ni alloys. Hence, this paper calculates the formation energy, electronic structure, elastic modulus, and elastic anisotropy of the precipitated phase in Mg-Gd-Ni alloys using first principles. Calculations of formation energies and elastic constants demonstrate that MgGdNi4, Mg2Ni, 18R-LPSO, Mg2Gd, and 14H-LPSO possess commendable thermodynamic and mechanical stability. Elastic modulus calculations reveal a significant increase in the elastic modulus of magnesium, especially the bulk modulus, upon the addition of Gd and Ni elements, increasing from 34.5 GPa to a peak of 84.9 GPa. Furthermore, the strength increments of the corresponding precipitated alloys, calculated based on the elastic modulus, underscore MgGdNi4 as exhibiting the most significant strength increment. The elastic anisotropy of each second phase is evaluated using the elastic anisotropy factor, the three-dimensional surface, and the projection onto each two-dimensional plane. The order of elastic modulus anisotropy for shear and Young's modulus is MgGdNi4 > Mg2Ni > 18R-LPSO > Mg2Gd > 14H-LPSO. This study provides valuable data for regulating properties in magnesium alloys.

Impact of gadolinium doping on BiFeO3-PbZrO3 for energy storage applications: Structural, microstructural, and thermistor properties

The solid-state reaction technique is used to prepare the Gd-doped BiFeO3-PbZrO3 at concentrations x = 0.05, 0.10, 0.15, and 0.20 with chemical formula 0.5(BiGdxFe1-xO3)-0.5(PbZrO3). Room-temperature XRD data are used to compute structural characteristics, such as dislocation density, microstrain, crystallite size, and percentage of crystallinity. The SEM micrographs indicate the spherical, tightly packed nature of materials with limited porosity. The extent to which the composites work at high temperatures (175–400 °C) as NTC thermistors. Understanding the properties of the NTC thermistor requires the calculation of the resistor constant, sensitivity index, and activation energies. Based on the frequency- and temperature-dependent AC conductivity of the composites, a high density of states was calculated.

Quasi-Classical Trajectory Calculation of Rate Constants Using an Ab Initio Trained Machine Learning Model (aML-MD) with Multifidelity Data.

Machine learning (ML) provides a great opportunity for the construction of models with improved accuracy in classical molecular dynamics (MD). However, the accuracy of a ML trained model is limited by the quality and quantity of the training data. Generating large sets of accurate ab initio training data can require significant computational resources. Furthermore, inconsistent or incompatible data with different accuracies obtained using different methods may lead to biased or unreliable ML models that do not accurately represent the underlying physics. Recently, transfer learning showed its potential for avoiding these problems as well as for improving the accuracy, efficiency, and generalization of ML models using multifidelity data. In this work, ab initio trained ML-based MD (aML-MD) models are developed through transfer learning using DFT and multireference data from multiple sources with varying accuracy within the Deep Potential MD framework. The accuracy of the force field is demonstrated by calculating rate constants for the H + HO2 → H2 + 3O2 reaction using quasi-classical trajectories. We show that the aML-MD model with transfer learning can accurately predict the rate constants while reducing the computational cost by more than five times compared to the use of more expensive quantum chemistry training data sets. Hence, the aML-MD model with transfer learning shows great potential in using multifidelity data to reduce the computational cost involved in generating the training set for these potentials.

Anti‐Coronavirus Activity of Certain Herbacetin Derivatives, A Theoretical Study

AbstractFlavonoids are natural products commonly found in the human diet with anti‐viral activity. The electrochemical activity of flavonoids is effective in their inhibitory properties. Herbacetin is an anti‐coronavirus drug from the flavonoid family. To understand structure‐electrochemical activity relations, ab initio calculations on some selected herbacetin derivatives were carried out using Gaussian 09 in B3LYP/6‐311G*. The effect of the position and type of the various substituents in the ring A of the flavone backbone are considered. The oxygen charge density of the hydroxyl group on C8 (O8) in the considered herbacetins was compared using nuclear quadrupole coupling constants (NQCC) calculations. Results showed that the presence of the amino group in the ortho position of O8 has the most significant effect on increasing the charge density of the O8 atom (O8‐NQCC=9.23 MHz). Based on the proposed mechanism of these drugs, ortho‐amino herbacetin is expected to show a significant anti‐coronavirus effect. Comparison of calculated O8‐NQCCs of tangeretin and nobiletin with herbacetin shows that with the replacement of OH with OCH3, the charge density of oxygen atoms decreases (about 2 MHz). Therefore tangeretin and nobiletin have a lower drug effect than herbacetin. Natural bond orbital (NBO) results are in agreement with calculated NQCCs.

Kinetic analysis of monomolecular cracking of normal Alkanes (C4[sbnd]C6) over Brønsted Acid site of Zeolitic type catalyst with energetic evaluation of transition states using Quantum-Chemical modeling

The work aims to determine the kinetic parameters of reactions for production of light olefins via catalytic cracking reactions of C4–C6 n-alkanes based on the energy characteristics of the transition state using quantum chemical calculations. Cracking reactions of C4–C6 n-alkanes proceed via protolytic mechanism on the Brønsted acid sites of zeolite-containing catalysts. For kinetic studies in this work, the thermochemical parameters of the intermediate stages, including hydrocarbon adsorption and transition state were determined, then the activation energies and rate constants were determined over the temperature range of catalytic cracking process from 773 to 903 K (500–630 °C).The results showed that DFT method in combination with B3LYP and ωB97X-D functionals, and 3–21 G basis demonstrated quite high accuracy in determining thermochemical parameters, including enthalpy, entropy and Gibbs free energy at both energetic levels of adsorption and transition state. Then, modeling continued by calculations of activation energies and rate constants of reactions. Obtained kinetic parameters made it possible to determine the reactivity of hydrocarbons with different chain length. It was obtained that the rate constants of butane cracking reactions with the formation of ethylene are 54–90 times higher than the formation of propylene. The rate constants of pentane cracking reactions with the formation of butylene are on average 5 times higher than the formation of propylene. The rate constants for hexane cracking reactions with the formation of butylene are 2.9–3.7 times higher compared to the formation of propylene.