Reactive Force Field Research Articles

Laser powder bed fusion sintering mechanism of phenolic resin investigated by ReaxFF molecular dynamics simulations

ABSTRACT This study presents an innovative approach utilising molecular dynamics simulations to elucidate the polymerisation and neck formation mechanisms of phenolic resin during laser powder bed fusion (L-PBF). By developing system and dual-particle models and employing infrared thermal imaging, we established a heat source model for phenolic resin under varying parameters. Our molecular dynamics simulations, using the ReaxFF reactive force field, indicate that high-power lasers significantly enhance cross-linking, achieving a peak polymerisation degree of 78.9% at 30W and 35W power levels. Conversely, increased scanning speed slows product degradation, reducing the polymerisation degree. The interplay of laser power and scanning speed influences polymerisation, with total input energy and heating rate impacting polymerisation and molecular size. Additionally, we investigated neck formation, revealing that small vortices evolve into larger ones during sintering, promoting neck formation. Optical microscopy confirmed diverse neck shapes under different conditions. Quantitative data showed that at a scanning speed of 1000 mm/s, the polymerisation degree reached 93%, with only 2 molecules remaining post-simulation. At 30W power, the largest individual molecule observed was C849H703O117. This research offers crucial insights for selective laser sintering processes, emphasising the importance of high energy input and optimal heating rates for well-formed necks.

Insights into the co-pyrolysis interaction of cellulose and Zhundong coal via ReaxFF molecular dynamics simulation

Experiments on the co-pyrolysis of coal and cellulose were conducted using a fixed-bed reactor in this paper. The results demonstrated that co-pyrolysis increases gas and char yields while reducing tar yield. The reactive force field molecular dynamics (ReaxFF MD) was then used to simulate co-pyrolysis in order to analyze the mutual reaction between coal and cellulose from the perspective of carbon skeleton, enabling the co-pyrolysis mechanism to be examined precisely. The results demonstrated that co-pyrolysis accelerates the crosslinking of cellulose fragments and coal char. The cellulose-derived component in cross-linked char (char products containing both cellulose and coal fragments) rises from 0.21 wt% at 2000 K to 12.82 wt% at 3000 K, resulting in higher char production. The examination of the yields and distribution of co-pyrolysis products at 2400 K reveals that the volatiles generated by cellulose and coal char undergo mainly crosslinking reaction, resulting in a lower tar yield and a higher inorganic gas yield. Due to the combination of oxygen-containing functional groups in the coal char with cellulose volatiles and free hydroxyl groups, the oxygen-containing active functional groups were consumed, rendering the cross-linked char more stable and inactive, thereby suppressing coal polymerization.

Atomic oxygen erosion mechanism of polyimide via reactive molecular dynamics simulation and density functional theory calculation

Atomic oxygen (AO) causes serious oxidative degradation on polymeric materials in the space environment, yet understanding its reaction mechanism is a challenging task. Herein, we primarily investigate the reaction sites and reaction paths of pure polyimide material to AO erosion and propose a modification strategy involving electron-withdrawing groups to enhance the material's resistance to AO with density functional theory (DFT) and reactive force field molecular dynamics (ReaxFF MD). DFT calculations reveal that AO erosion is an electrophilic reaction, which preferentially interacts on the benzene ring with pronounced electron density distribution on the third part of the polyimide molecule. ReaxFF MD simulations validate this finding and provide additional reaction pathways that are divided into the early-stage reactions and later secondary reactions. In the early stage, only small number of AOs take part in the reactions that include the formation of CO bonds and ring opening processes. These reactions are relatively slow and majorly determine the AO resistance of the material. In the subsequent stage, AO predominantly reacts with reactive species and radicals generated from earlier reactions, leading to fast degradation. With these findings, we propose a strategy to enhance the AO resistance by introducing electron-withdrawing functional groups in the polyimides. As exemplified, the polyimide with -CF3 group shows 21.1% lower erosion yield than unmodified polymer. The present study gives a deep insight for the mechanism of AO erosion on polyimide by exploring its reaction sites and provides valuable theoretical guidance for improving the material's resistance to erosion.

Simultaneous improvement in the elastic and fracture properties of graphene-epoxy nanocomposites–a computational perspective

The incorporation of stiff nano-additives (such as graphene) into a relatively soft polymer material (such as epoxy) usually leads to an improvement in elastic properties (i.e., Young's modulus) at the expense of fracture properties (i.e., tensile strength and toughness). Despite over a decade of research in polymer nanocomposites, we still lack a clear understanding of their structure-property relationships, which limits us from enhancing both elastic and fracture properties concurrently. Here, we performed large-scale reactive molecular dynamics simulations to study the deformation and fracture of model graphene/epoxy systems under uniaxial tension. A computationally efficient reactive force field was developed for graphene-epoxy system, allowing covalent bond formation, and breaking, which is crucial to model cross-linking in model epoxy as well as fracture. It was found the mechanical properties of the nanocomposite are very sensitive to the strength of the graphene-epoxy interface. As expected, elastic modulus increases with the interfacial strength. However, there appears to be an optimal interfacial strength to enhance the tensile strength and toughness. This is due to stress concentration occurring near the graphene edges at high interfacial strength, which leads to premature fracture. We show that by appropriately selecting an intermediate interface strength, one can simultaneously improve the ultimate tensile strength, toughness and the Young's modulus of the nanocomposite epoxy at ultra-low (∼0.2 % by weight) loading fraction of graphene additives. Our findings highlight the critical importance of properly engineered additive-matrix interfacial strength to develop high-performing polymer nanocomposites that are concurrently stiff, strong as well as tough.

Optimization of molecular dynamics in hydrogen production through phenol gasification in supercritical water

Phenol serves as a crucial intermediate in the biomass conversion process, and its solubility or conversion rate in the aqueous phase is a determining factor for the prerequisite conditions and rate of biomass gasification for hydrogen production. In this study, we utilized the ReaxFF reactive force field in conjunction with density functional theory to investigate the optimized molecular dynamics of phenol gasification for hydrogen production in supercritical water. The research systematically explored phenol gasification for hydrogen production in supercritical water under varying reaction temperatures, residence times, and relative concentrations, comprehensively analyzing the gasification mechanisms. Results indicate that under conditions of 4000 K, 0.4644 g mL−1, and 750,000 steps residence time, the hydrogen gasification rate reaches a maximum of approximately 80 %. The reaction temperature exhibits a positive correlation with gasification efficiency, while residence times and relative concentration also impact hydrogen yield. Furthermore, phenol in supercritical water predominantly exhibits two ring-opening pathways: one involves the initial dehydrogenation by removing a hydrogen atom connected to phenol itself, followed by subsequent ring-opening; the other entails the prior removal of a hydrogen atom attached to the hydroxyl group, leading to eventual ring-opening. The energy disparity for the final ring-opening in these pathways is not significant, both approximately at 880 Ha. In this system, H2O not only serves as the reaction medium but also provides essential free radical ions for the reaction, ultimately resulting in hydrogen gas generation. This study offers theoretical guidance for enhancing hydrogen production in biomass supercritical water processes.

Prediction of a Novel Electromechanical Response in Polar Polymers with Rigid Backbones: Contrasting Furan-Derived Nanothreads to Poly(Vinylidene Fluoride).

Syn furan nanothreads have all oxygen atoms arranged on one side of the thread backbone; these polar threads present intriguing opportunities in electromechanical response owing to their rigid ladder-like backbone. We retrained a C/H/O reactive force field to simulate their response to external electric field for both end-anchored individual threads and bulk nanothread crystals, contrasting the results to those for poly(vinylidene fluoride) (PVDF) polymer. Whereas the field induces a length-independent torque in PVDF through backbone rotation about σ bonds, furan-derived nanothreads generate a length-dependent torque by progressively twisting their rigid backbone. This mode of response couples the rotational history of the electric field to axial tension in the anchored thread. In simulations of densely packed syn furan nanothread crystals without anchors, the crystals pole in a field (∼3 GV/m at 300 K) similar to that seen in simulations of PVDF, suggesting that crystals of polar nanothreads can be ferroelectric.

Tribo-Chemical Reactions in DLC-Zirconia Sliding under Ethanol Gas Environment.

A reactive force field (ReaxFF) molecular dynamics simulation is performed for the sliding of diamond-like carbon (DLC) and yttria-stabilized zirconia (YSZ) under an ethanol gas environment, motivated by the previous experiment of ultralow friction phenomenon (friction fade-out). We observe (i) dissociation of ethanol into ethoxy and hydrogen, both of which simultaneously adsorb on the YSZ surface, and (ii) dissociation of ethanol into ethyl and hydroxy, the former of which forms a bond with another ethanol molecule and the latter of which adsorbs on the DLC surface. Reaction (i) is enhanced by the sliding motion, but occurs even without it, while reaction (ii) only occurs during sliding with a sufficiently high load pressure. The potentials of mean force for the two reactions are also calculated combining the steered MD and Jarzynski equality. It is shown that the activation energies of reactions (i) and (ii) are significantly lowered by the YSZ and DLC surfaces, respectively, as compared to those in a vacuum. The resultant activation energy is higher for reaction (ii) than for reaction (i).

Fracture of Epoxy Networks Using Atomistic Simulations.

Predicting fracture properties through all-atomistic simulations poses challenges due to classical force field limitations in breaking covalent bonds and the computational demands of reactive force fields like ReaxFF. In addressing this, we propose a scale-bridging method for forecasting the fracture behavior of highly cross-linked epoxy combining classical force fields, the LAMMPS package REACTER, and for bond breaking a parameter based on experimental distance criterion. In our analysis, we anticipate the macroscopic fracture energy GC of the epoxy network through the application of a continuum fracture mechanics model developed for fibrils. In addition, we extract the value of the stress intensity factor KI. This modeling approach is specifically implemented for a frequently used epoxy system that consists of bisphenol F and DETDA hardener. Notably, our results demonstrate a robust correlation with existing literature and experimental studies. Moreover, our approach boasts a substantial computational time advantage, facilitating calculations that are significantly faster compared to those performed using reactive force fields.

Influence essential of current on electrochemical plasticization of single-crystal copper

Despite the long-standing identification of electrochemical plasticization (EP) in the metal surface layer, the mechanisms governing the impact of electric current density on EP remain incompletely understood. This study investigates the effect of current density (ranging from 0 mA cm−2 to 10.0 mA cm−2) on EP during electrochemical cold drawing of single-crystal copper in a 0.35 mol L−1 dilute H2SO4 electrolyte through microstructural characterizations and reactive force field molecular dynamic simulations. The results indicate that with increasing density, more atoms in the high-energy {110} and {001} planes in the copper surface are selectively dissolved, causing the atoms in the low-energy uncorroded {111} planes to become more loosened. This activates more abundant dislocations in a multi-slip way, thereby facilitating dislocation entanglements to reconfigure into movable short-range wavy dislocations and decreasing dislocation density through reactions, ultimately resulting in improved EP. However, when the density exceeds 6.7 mA cm–2, an opposite effect is observed due to the dissolution of fewer atoms resulting from enhanced local passivation.

Molecular Dynamics Simulations of Soft and Reactive Landing of Proteins Desorbed by Argon Cluster Bombardment.

Reactive molecular dynamics (MD) simulations were conducted to investigate the soft and reactive landing of hyperthermal velocity proteins transferred to a vacuum using large argon clusters. Experimentally, the interaction of argon cluster ion beams (Ar1000-5000+) with a target biofilm was previously used in such a manner to transfer lysozymes onto a collector with the retention of their bioactivity, paving the way to a new solvent-free method for complex biosurface nanofabrication. However, the experiments did not give access to a microscopic view of the interactions needed for their full understanding, which can be provided by the MD model. Our reactive force field simulations clarify the landing mechanisms of the lysozymes and their fragments on collectors with different natures (gold- and hydrogen-terminated graphite). The results highlight the conditions of soft and reactive landing on rigid surfaces, the effects of the protein structure, energy, and incidence angle before landing, and the adhesion forces with the collector substrate. Many of the obtained results can be generalized to other soft and reactive landing approaches used for biomolecules such as electrospray ionization and matrix-assisted laser desorption ionization.

Insights into molecular and bulk mechanical properties of glassy carbon through molecular dynamics simulations and mechanical tensile testing

With increasing interest in the use of glassy carbon (GC) for a broad range of application areas, the need for developing a fundamental understanding of its mechanical properties has come to the forefront. Furthermore, recent theoretical and modeling works that highlight the synthesis of GC via the pyrolysis of polymer precursors has explored the possibilities of a revisit to the investigation of their mechanical properties at a fundamental level. Although there are isolated reports on the experimental determination of its elastic modulus, insights into the stress-strain behavior of a GC material under tension and compression obtained through simulations, either at the molecular level or for the bulk materials, are missing. This study fills the gap at the molecular level and investigates the mechanical properties of GC using molecular dynamics (MD) simulations, which model the atomistic-level formation and breaking of bonds using bond-order-based reactive force field formulations. The molecular model considered in this simulation has a characteristic 3D cage-like structure of five-, six-, and seven-membered carbon rings and graphitic domains of a flat graphene-like structure. The GC molecular model was subjected to loading under varying strain rates (0.4, 0.6, 1.25, and 2.5 ns−1) and temperatures (300 K–800 K) in each of the three axes: x, y, and z. The simulations show that the GC nanostructure has distinct stress-strain curves under tension and compression. In tension, MD modeling predicted a mean elastic modulus of 5.71GPa for a single GC nanostructure with some dependency on the strain rate and temperature, whereas, in compression, the elastic modulus was also found to depend on the strain rate and temperature and was predicted to have a mean value of 35 GPa. To validate the simulation results and develop experimental insights into the bulk behavior, mechanical tests were conducted on dog-bone-shaped testing coupons that were subjected to uniaxial tension and loaded until failure. The GC test coupons demonstrated a bulk modulus of 17 ±2.69 GPa in tension, which compares well with those reported in the literature. However, comparing MD simulation outcomes to those of uniaxial mechanical testing reveals that the bulk modulus of GC in tension found experimentally is higher than the modulus of single GC nanostructures predicted by MD modeling, which inherently underestimates the bulk modulus. With regard to failure modes, the MD simulations predicted failure in tension accompanied by the breaking of carbon rings within the molecular structure. In contrast, the mechanical testing demonstrated that failure modes are dominated by brittle failure planes largely due to the amorphous structure of GC.

Gas phase product evolution during high temperature pyrolysis of PTFE: Development of ReaxFF simulation protocol

The formation of products of incomplete destruction (PIDs) from fluoropolymer incineration is poorly understood and it is imperative to environmental impact studies. The lack of analytical standards limits the experimental approaches targeting product analysis. To navigate this challenge, computational modeling of the thermal degradation of fluoropolymers provides simulated product distributions. However, it is essential to benchmark reactive forcefields to accurately simulate fluoropolymer pyrolysis. The present work describes a protocol to perform accurate simulations of the thermal degradation of fluoropolymers to probe the PIDs. The ReaxFF force field was applied to reproduce the experimental bulk density and glass transition temperature of polytetrafluoroethylene (PTFE). The benchmarked methodology developed has been extended to provide simulated product distributions and mechanistic insights which are in excellent agreement with primary literature. On the basis of our simulated data, we observe a degradation mechanism that proceeds through three primary steps: 1) initiation of random backbone cleavage, 2) C2F4 unzipping through β–scission (as opposed to CF2 unzipping), and 3) secondary product formation. An extension of the developed protocol has the potential to simulate the thermal degradation of non-polymeric per- and polyfluoroalkyl substances (PFASs) in addition to long-chain fluoropolymers.

Pyrolysis and oxidation mechanisms of ethylene and ethanol blended fuel based on ReaxFF molecular dynamics simulation

To gain detailed atomic-level insights into the reaction mechanisms associated with the oxy-fuel combustion of ethylene and ethanol, ReaxFF reactive force field molecular dynamics simulations were performed to analyze the behavior of their high-temperature pyrolysis and oxidation. Results showed that the main reaction of pure ethylene involves the formation of long carbon chains by C–C polymerization in an oxygen-free environment. The polycondensation-cyclization of long carbon chains significantly contributes to the formation of polycyclic aromatic hydrocarbons (PAHs). The addition of ethanol enriches the initial reaction pathways of ethylene. For instance, ethanol participates in the following reactions: C2H4 + C2H6O → C4H10O, C2H6O + C2H4 → C2H5 + C2H5O, and C2H6O + C2H4 → C2H5 + H2O + C2H3. Ethanol inhibits the growth of long carbon chains, with a more pronounced effect at higher ethanol concentrations. In an oxygen atmosphere, the decay rate of ethylene decreases significantly, and its main reaction pathway involves dehydrogenation and oxidation with the assistance of OH, HO2, H, and O2. The final products are released in the form of CO, CO2, and H2O. In addition, the formation of soot particles is mainly divided into three steps: (i) ethylene aggregates to form long carbon chains, (ii) rearrangement and cyclization of long carbon chains, and (iii) growth of PAHs.

Co-pyrolysis of subbituminous coal and lignin at isothermal and non-isothermal conditions: A ReaxFF molecular dynamics simulation

Understanding the co-pyrolysis behavior of sub-bituminous coal and lignin not only contributes to the efficient and clean use of coal but also enables low carbon emissions. The behavior and product evolution of pure coal, pure lignin, and co-pyrolysis systems under isothermal and non-isothermal conditions were explored using reactive force field molecular dynamics (ReaxFF MD) simulation. Through multiple isothermal simulation processes, the co-pyrolysis system showed an inhibition effect, promoting the generation of heavy compounds and inhibiting the generation of tar and gas. The inhibition effect at 2400 K was the most significant in the pyrolysis period. A similar phenomenon was found in the non-isothermal pyrolysis process at 2 K/ps. In addition, the H2 yield under non-isothermal conditions was lower than the calculated value. By distinguishing the same element from different sources, there were three types of H2 (Hcoal2, HcoalHlignin, and Hlignin2). Subsequently, the H atoms in lignin prefer to produce H2 than that in coal during co-pyrolysis. Finally, we further explored the evolution behavior of the configurations during the pyrolysis of non-isothermal coal and lignin systems. These findings enrich the theoretical information on the interaction between coal and lignin, providing the behavior of Hcoal and Hlignin atoms in the co-pyrolysis system.

Advancing tribological simulations of carbon-based lubricants with active learning and machine learning molecular dynamics

The need to move toward more sustainable lubricant materials has sparked an ever growing interest on the tribological performances of additives based on environmentally friendly molecules, such as carbon-based compounds, and green liquid media as aqueous solutions. The prediction of the solubility of the additives into the liquid and the tribochemistry of decomposition and polymerization of the additive molecules under harsh conditions is essential for understanding the atomistic mechanisms leading to the formation in situ of the carbon-based lubricious tribofilms so effective in reducing friction and wear at solid interfaces. To this extent, the application of tools like ab initio molecular dynamics based on first-principle density functional theory is severely hindered by the size of the systems of interests and the need to simulate their dynamics over relatively long times. To enable tribological simulations with quantum accuracy for a first time, we develop a workflow for smart configuration sampling in active learning, to obtain machine learning interatomic potentials which are shown to be sufficiently robust and accurate also in the characteristic harsh conditions generated by high loads and shear rates. Focusing on glycerol rich lubricants, we apply this active learning strategy to generate a neural network potential to simulate the formation and behavior of nanometer thick molecular tribofilms. The simulations reveal the superior accuracy of the machine learning approach with respect to classical molecular dynamics with reactive force fields, and pave the way for more promising in depth exploration of novel carbon-based lubricants.

A theoretical model considering the photochemical and photothermal behavior of arc radiation-induced gassing materials ablation

In this study, we introduce a theoretical model designed to explore both the photochemical and photothermal behavior of arc plasma radiation-induced ablation in gassing materials. We employ time-dependent density functional theory to analyze the photochemical behavior, while reactive force field molecular dynamics are used to explore the photothermal behavior. The phenomena, behavior and consequences of valence shell electronic excitation are analyzed in terms of ultraviolet (UV) absorption, electron-hole distribution, and Mayer bond order. Based on the photochemical findings, we apply a periodic electric field that corresponds to the vibration frequency of the permanent dipole moment to simulate infrared radiation, and convert UV photon energy into atomic kinetic energy to analyze UV radiation. This atomic-scale insight into photothermal behavior enables us to identify the final composition of ablation gases, including H2, CO, H2O, NH3, as well as specific cyanides, amines, and hydrocarbons. The results of the theoretical model and physical properties indicate that the concentration of hydrogen-containing gases in the ablation gas significantly affects the arc extinguishing capabilities of different polymers. Finally, we propose modification schemes suitable for polymers in power circuit breakers, considering UV absorption and smoke black production. Additionally, we present the potential application of theoretical models for calculating the ablation rate, necessitating further in-depth re-search.

Simulations on coal water slurry gasification by molecular dynamics method with ReaxFF.

Coal water slurry (CWS) is a new type of liquid coal product with low pollution, which is mainly used in the chemical industry to produce syngas (CO + H2). It is of great significance to study the microscopic mechanism of CWS gasification reaction for improving the efficiency of coal gasification. In this paper, the method of molecular dynamics based on reaction force fields (ReaxFF-MD) is used to study the gasification process of CWS/O2 system at different temperatures. The results show that, in the range of 1600-2400 K, the macromolecular network structure of lignite is decomposed into a large number of small molecular structures and a small number of light tar free radical fragments, and the types and quantities of reaction products increased rapidly. At 2400-4000 K, the free radical fragments of light tar are further decomposed and reacted with gasification agents, but the types and quantities of reaction products have little change. At 3600 K, a full gasification reaction occurred in the system, and the content of syngas is the highest. The model was established and optimized by Materials Studio (MS) software. Based on ReaxFF-MD method, Lammps software was used to simulate the gasification process of CWS/O2 system, and the reaction force field files containing C, H, O, N, and S element were used. By calculating the activation energy of gasification reaction, the rationality of the model and calculation method was illustrated. The post-processing of the results was implemented using OVITO, ChemDraw software, and self-programmed Python scripts.

Detailed Reaction Kinetics for Hydrocarbon Fuels: The Development and Application of the ReaxFFCHO-S22 Force Field for C/H/O Systems with Enhanced Accuracy.

Efficient and accurate reactive force fields (e.g., ReaxFF) are pivotal for large-scale atomistic simulations to comprehend microscopic combustion processes. ReaxFF has been extensively utilized to describe chemical reactions in condensed phases, but most existing ReaxFF models rely on quantum mechanical (QM) data nearly two decades old, particularly in hydrocarbon systems, constraining their accuracy and applicability. Addressing this gap, we introduce a reparametrized ReaxFFCHO-S22 for C/H/O systems, tailored for studying the pyrolysis and combustion of hydrocarbon fuel. Our approach involves high-level QM benchmarks and large database construction for C/H/O systems, global ReaxFF parameter optimization, and molecular dynamics simulations of typical hydrocarbon fuels. Density functional theory (DFT) computations utilized the M06-2X functional at the meta-generalized gradient approximation (meta-GGA) level with a large basis set (6-311++G**). Our new ReaxFFCHO-S22 model exhibits a minimum 10% enhancement in accuracy compared to the previous ReaxFF models for a large variety of hydrocarbon molecules. This advanced ReaxFFCHO-S22 not only enables efficient large-scale studies on the microscopic chemical reactions of more complex hydrocarbon fuel but also can extend to biofuels, energetic materials, polymers, and other pertinent systems, thus serving as a valuable tool for studying chemical reaction dynamics of the large-scale hydrocarbon condensed phase at an atomistic level.

Polyethylene deflagration characterization and kinetic mechanism analysis

In this paper, the combustion process of polyethylene (C100H202) was simulated by experiment and Reaction Force Field molecular dynamics (ReaxFF MD) simulation, and the influence of density and temperature on the deflation of C100H202 was investigated. The flame propagation characteristics of C100H202 with different concentrations were studied by the Hartmann experiment system, and the pyrolysis characteristics of C100H202 under N2 and O2 atmospheres were studied by the TG test. The pyrolysis activation energy of C100H202 in N2 and O2 atmospheres is 72.160 kJ/mol and 92.356 kJ/mol, respectively, which is consistent with the reaction activation energy of 97.110 kJ/mol calculated by simulation. In addition, it is found through simulation that the increase in system density will increase the generation and consumption of intermediate products such as C2H4, which explains the phenomenon of more intense detonation when the concentration of C100H202 increases from 0.0002 g/cm3 to 0.0005 g/cm3 in dust ignition experiment from the molecular level. The results show that physical methods such as cooling down and releasing inert gas and chemical methods that consume functional groups have significant effects on the inhibition of hydrocarbon deflagrations from a microscopic point of view, and provide theoretical support for the study of the inhibition of hydrocarbon deflagrations.

Derivation of Morse potential

The Morse potential is widely used in chemistry, physics, and material science to describe interatomic interactions. We show that the Morse potential can be derived from a simple screened charge model accounting for the shielding of the nuclear charge by electron density. In this model, the parameter governing the width of the potential is related to the average shielding strength and the exponents of the atomic orbitals used in electronic structure calculations. The parameter representing the bond dissociation energy of a diatomic molecule is derived by combining the quantum mechanical covalent and classical electrostatic interactions. Moreover, the revealed connection between the parameters of the Morse potential and Pauling’s bond order and electronegativity provides insight into the relation between the classical and quantum mechanical descriptions of chemical bonds. This derivation of the Morse potential from the atomic quantities is expected to contribute to the development of the new basis sets incorporating Slater-type orbitals for electronic structure calculations and the transferable reactive force fields for molecular dynamics simulations. Furthermore, this interpretation of the Morse potential helps to understand the relationships between widely used chemical concepts, including effective atomic charge, bond dissociation energy, electronegativity, and bond order.