Lennard-Jones Potential Parameters Research Articles

Relationship between Lennard-Jones potential and physico-chemical parameters

Relationship between Lennard-Jones potential and physico-chemical parameters

Exploring HCl-HCl interactions: QZVPP calculations, improved Lennard-Jones potential, and second virial coefficient analysis for thermodynamics and industrial applications.

In this paper, we present a comprehensive analysis of HCl-HCl interactions, including QZVPP calculations, energy fitting, conformation validation, and the determination of the second virial coefficient B using improved Lennard-Jones (ILJ) potential parameters. To acquire accurate interaction energies, initial QZVPP calculations are performed on approximately 1851 randomly generated HCl-HCl conformations. Then, these energies are used to fit an improved Lennard-Jones potential energy surface, allowing for a robust description of HCl-HCl interactions. The ILJ potential parameters are then used to validate particular HCl dimer conformations, ensuring their stability and consistency with experimental observations. The correlation between calculated and experimental conformations strengthens the validity of the ILJ potential parameters. In addition, the second viral coefficient B is calculated at various temperatures using the ILJ potential. The obtained B values are compared to experimental data, demonstrating close agreement, and validating the ILJ potential's ability to accurately capture the intermolecular interactions and gas-phase behavior of the HCl-HCl system. The results of this study demonstrate the effective implementation of QZVPP calculations, energy fitting, and ILJ potential parameters in validating HCl-HCl conformations and accurately determining the second virial coefficient B. The high degree of concordance between calculated B values and experimental data demonstrates the validity of the ILJ potential and its suitability for modeling HCl-HCl interactions. This research contributes to a greater comprehension of HCl-HCl interactions and their implications for numerous chemical and atmospheric processes. The validated conformations, energy fitting method, and calculated second virial coefficients provide valuable instruments for future research and pave the way for more accurate modeling and simulations of HCl-HCl systems.

Analyze molecular interaction for mixture of argon and particles with different sizes

This article elaborates on molecular dynamics simulation, which is a technology that supports us in analyzing the structure and dynamics of materials and their properties at a microscopic level. In this article, the molecular dynamics simulation develops on Lennard-Jones potential. The simulation is based on the fundamental understanding between Argon-Argon molecules. The application for running molecular dynamics simulation is Moldy. The Argon particles size is changed by altering van der Waals radius from Lennard-Jones potential parameters, and the mixture of Argon and different sizes particles will be simulated by Moldy. The average potential energy is collected and compared. It discusses how the size of particles affect the average potential energy. Moreover, the trend of potential energy respects to timesteps for each molecule is depicted and compared graphicly by Gnuplot. It discusses how the potential energy changes according to timesteps for different sizes particles. In the end, the result is collected and summarized. It discovers that potential energy increases slowly when particles sizes increase, and the potential energy decreases significantly when particles sizes decrease. In addition, it founds out that molecules with different sizes have a noticeable change initially. Oddly, there is no observation of significant changes in the potential energy of the original molecule. Moreover, the initial decrease for molecules that increase in size is not as significant as that for molecules that decrease in size.

Data-Driven Approach to Coarse-Graining Simple Liquids in Confinement.

We propose a data-driven framework for identifying coarse-grained (CG) Lennard-Jones (LJ) potential parameters in confined systems for simple liquids. Our approach involves the use of a Deep Neural Network (DNN) that is trained to approximate the solution of the Inverse Liquid State (ILST) problem for confined systems. The DNN model inherently incorporates essential physical characteristics specific to confined fluids, enabling an accurate prediction of inhomogeneity effects. By utilizing transfer learning, we predict single-site LJ potentials of simple multiatomic liquids confined in a slit-like channel, which effectively replicate both the fluid structure and molecular force of the target All-Atom (AA) system when the electrostatic interactions are not dominant. In addition, we showcase the synergy between the data-driven approach and the well-known Bottom-Up coarse-graining method utilizing Relative-Entropy (RE) Minimization. Through the sequential utilization of these two methods, the robustness of the iterative RE method is significantly augmented, leading to a remarkable enhancement in convergence.

Self-Consistent Set of Lennard–Jones Potential Parameters for Molecular Dynamics Simulations of Oxide Materials

Self-Consistent Set of Lennard–Jones Potential Parameters for Molecular Dynamics Simulations of Oxide Materials

Self-Consistent Set of Lennard–Jones Potential Parameters for Molecular Dynamics Simulations of Oxide Materials

A forcefield for high-performance molecular dynamics (MD) simulation of inorganic oxide substances, including borosilicate glasses, based on a combination of electrostatic interactions with the 6–12 type of Lennard–Jones potentials is developed. The forcefield parameters are selected to reproduce the structures and bulk moduli of the binary oxides of a wide spectrum of elements. The proposed forcefield is able to accurate reproduce structures of minerals containing two to three types of cations during the MD simulations. Application of the 6–12 potential makes it possible to carry out simultaneous MD simulations of the organic and inorganic phases, for example, in modeling composite materials with mineral and glass fillers.

Where Lennard-Jones Potentials Fail: Iterative Optimization of Ion-Water Pair Potentials Based on Ab Initio Molecular Dynamics Data.

The use of the Lennard-Jones (LJ) potential in computer simulations of aqueous electrolyte solutions is widespread. The standard approach is to parametrize LJ potential parameters against thermodynamic solution properties, but problems in representing the local structural and dynamic properties of ion hydration shells remain. The r-12-term in the LJ potential is responsible for this as it leads to overly repulsive ion-water interactions at short range. As a result, the LJ potential predicts blue-shifted vibrational peaks of the cations' rattling mode and too large negative ion hydration entropies. We demonstrate that cation-water effective pair potentials derived from ab initio MD data have softer short-range repulsions and represent hydration shell properties significantly better. Our findings indicate that replacing the LJ potential with these effective pair potentials offers a promising route to represent thermodynamic solution properties and local interactions of specific ions with nonpolarizable force field models.

Diffusion coefficient calculation of iron in liquid lead using molecular dynamics method with new mixing rule for Lennard-Jones potential parameters

The diffusion coefficient data of materials are crucial for several applications, and can be calculated theoretically up to considerable accuracies. Using molecular dynamics simulation it is possible to compute this property for several conditions as temperature and pressure. The corrosion phenomena of steel types in the fast nuclear reactor can be correlated and studied based on the the diffusion process of iron atoms that dissolve into a liquid lead coolant via molecular dynamics methods using certain potential energy. A widely type of the interatomic interaction potential of materials is the Lennard-Jones potential. Regarding this potential, for a pair of different elements A and B, we can determine the potential parameter (

Simulating diffusion in the conditions of vapor-liquid phase transition by the molecular dynamics method

The molecular dynamics calculations of diffusion coefficients in binary Lennard-Jones systems have been carried out. The parameters of Lennard-Jones potentials correspond to argon and krypton atoms. The universal dependence of the reduced diffusion coefficient of krypton atoms on density for the homogeneous systems of low and middle densities is found. The deviations of the diffusion coefficients from the universal function are observed for the systems in the vapor – liquid phase transition region. The simulations have shown that almost all krypton atoms have situated inside the liquid phase of argon. Special numerical experiments have shown that the nanodroplets of argon are formed as a result of homogeneous nucleation and then the krypton atoms are captured by these droplets. This phenomenon decreases the diffusion coefficient of krypton atoms greatly.

Elementary, Atomic-Level Friction Processes in Systems with Metallic Inclusions—Systematic Simulations for a Wide Range of Local Pressures

In this work, simulations of friction at the atomic level were performed to evaluate the influence of inclusions coming from metallic nanoadditives in the friction pair. The simple 2D model was applied considering appropriate values of Lennard–Jones potential parameters for given sets of interacting atoms. The real sliding pairs were replaced by effective equivalents consisting of several atoms. The calculations were based on the pseudo-static approximation. The simplicity of the model enabled to repeat the fast calculations in a very wide range of local pressures and for several types of atomic tribopairs. The performed simulations demonstrated a strong dependence of the coefficient of friction (COF) on the atomic environment of the atoms constituting a tribopair. It was confirmed theoretically that the Mo-Fe pair is characterized by lower atomic COF than Fe-Fe, Cu-Fe, and Ag-Fe pairs. This points to the great applicational potential of metallic molybdenum coating applications in tribological systems. Moreover, it was demonstrated that, although Cu-Cu and Ag-Ag pairs are characterized by relatively high COF, they lower the friction as inclusions in Fe surfaces.

Laser excitation of BCl3 and consequential collision-induced reaction with carrier gases

A method is developed to demonstrate the laser excitation and consequential collision-induced reaction with carrier gases (G = He, N2, Ar, Xe) in isotope separation of BCl3. To investigate the mechanism of the transport process of excited molecules and the collision process with the carrier gases, the Lennard-Jones potential parameters of the molecule and the carrier gases, as well as the collision cross section σc and the repulsion distance parameter LR, are demonstrated. The transport equation (proposed by Eerkens in 2005) is used to study the transport mechanics of stimulated BCl3 molecules, including VT energy conversion and VV energy transfer caused by the collision of BCl3 molecules with the carrier gases during the supersonic pneumatic transportation, as de-excitation induced by transfer, dimer formation and dissociation, and so on.

Parameters (σ, ε) of Lennard-Jones for Fe, Ni, Pb for Potential and Cr based on Melting Point Values Using the Molecular Dynamics Method of the Lammps Program

Lennard-Jones potential is the potential energy of the bond interaction between two atoms or free molecules based on the distance between them. Molecular dynamics simulations can be used to calculate various physical properties of materials based on specific interaction potentials. One of the physical properties of a material is its melting point. This research was conducted to find the potential parameter values of Lennard-Jones metal Fe, Pb, Ni and Cr based on the melting point value of the material using the LAMMPS program. In this study the normalization of potential parameters is done by comparing the results of the simulation melting point with the experimental melting point. This research produces a Lennard-Jones potential parameter value which yields a melting point value that has a relatively small description.

Computer simulation of the crystal structure of tetrazino-tetrazine tetraoxide (TTTO) isomers with one and two independent molecules in the unit cell

The crystal structure prediction for two isomeric forms of tetrazino-tetrazine tetraoxide (TTTO), viz., [1,2,3,4]tetrazino[5,6-e][1,2,3,4]tetrazine 1,3,6,8-tetraoxide and [1,2,3,4] tetrazino [5,6-e] [1,2,3,4] tetrazine 1,3,5,7-tetraoxide was performed using an original procedure to obtain the optimized point charges that approximate the molecular electrostatic potential. The best computational models were used for simulation of the crystal packing of the molecules within the framework of the atom-atom potential function method with the refined Lennard-Jones potential parameters (6-12) by optimizing the unit cell parameters and localizing the minima on the potential energy surfaces of the crystal structures.

Predictability of Equation of State (EoS)-based Gas Hydrate Models for Single and Binary Gas Mixtures

The better models are necessary to design and understand the phase behavior of produced trapped natural gas from natural gas hydrates from subsea environments. Most of the models available in an open literature are primarily applicable at relatively low pressure condition thus making their use very limited for gas hydrate reservoir modeling. In order to produce methane from these gas hydrates, it is important to understand the phase behavior through suitable models which can be applied at in-situ reservoir conditions of high pressure and low temperature. These models can be used for better reservoir modeling of natural gas hydrate reservoir. In the present study the well-known Chen and Guo hydrate model has been used along with the set of several equations of state models (EoS). This model uses the published Lennard-Jones potential parameters obtained by fitting the L-J functions for typical gas species assuming the adsorption to be carried out in small cavities 5 12 . The code (in Matlab®) is developed based on the three famous equations of state Peng-Robinson (P-R), Patel-Teja (P-T), and Soave-Redlich-Kwong (SRK). We optimized the computed phase diagrams based on three EoS with experimental phase diagram data from literature and determined the model parameters for the model with less percentage average deviation. The present papers discusses about the modeling of pure CH 4 , C 2 H 6 , CO 2 and H 2 S and then discuss the work extended to model the phase behavior of binary gas mixture hydrates like CH 4 -C 2 H 6 , CH 4 -CO 2 and CH 4 -H 2 S. Model predictions are validated against the experimental data from the literature, and observed to be in well agreement for high pressure range, suggesting their applicability for gas hydrate reservoir modeling. Keywords: Binary Gas Mixture Hydrates, Equations of State, Fugacity, Hydrate Model, Natural Gas Hydrates

Transfer-Learning-Based Coarse-Graining Method for Simple Fluids: Toward Deep Inverse Liquid-State Theory.

Machine learning is an attractive paradigm to circumvent difficulties associated with the development and optimization of force-field parameters. In this study, a deep neural network (DNN) is used to study the inverse problem of the liquid-state theory, in particular, to obtain the relation between the radial distribution function (RDF) and the Lennard-Jones (LJ) potential parameters at various thermodynamic states. Using molecular dynamics (MD), many observables, including RDF, are determined once the interatomic potential is specified. However, the inverse problem (parametrization of the potential for a specific RDF) is not straightforward. Here we present a framework integrating DNN with big data from 1.5 TB of MD trajectories with a cumulative simulation time of 52 μs for 26 000 distinct systems to predict LJ potential parameters. Our results show that DNN is successful not only in the parametrization of the atomic LJ liquids but also in parametrizing the LJ potential for coarse-grained models of simple multiatom molecules.

Optimization of long range potential interaction parameters in ion mobility spectrometry.

The problem of optimizing Lennard-Jones (L-J) potential parameters to perform collision cross section (CCS) calculations in ion mobility spectrometry has been undertaken. The experimental CCS of 16 small organic molecules containing carbon, hydrogen, oxygen, nitrogen, and fluoride in N2 was compared to numerical calculations using Density Functional Theory (DFT). CCS calculations were performed using the momentum transfer algorithm IMoS and a 4-6-12 potential without incorporating the ion-quadrupole potential. A ceteris paribus optimization method was used to optimize the intercept σ and potential well-depth ϵ for the given atoms. This method yields important information that otherwise would remain concealed. Results show that the optimized L-J parameters are not necessarily unique with intercept and well-depth following an exponential relation at an existing line of minimums. Similarly, the method shows that some molecules containing atoms of interest may be ill-conditioned candidates to perform optimizations of the L-J parameters. The final calculated CCSs for the chosen parameters differ 1% on average from their experimental counterparts. This result conveys the notion that DFT calculations can indeed be used as potential candidates for CCS calculations and that effects, such as the ion-quadrupole potential or diffuse scattering, can be embedded into the L-J parameters without loss of accuracy but with a large increase in computational efficiency.

Effective Molecular Dynamics Model of Ionic Solutions for Large-Scale Calculations

A model of ionic solutions is proposed which can be used to calculate aqueous salt solutions in different nanostructures. The interaction potential of the model includes the Lennard-Jones potential and angularly averaged dipole–dipole and ion–dipole interactions. Lennard-Jones potential parameters for different ions are obtained. Characteristics of aqueous solutions at different salt concentrations are calculated using the molecular dynamics method. It is shown that the calculated values of the hydration shells of ions parameters are in good agreement with the theoretical and experimental data at a salt concentration of 1 mol/kg. The computational scheme used in the calculations is described. It is shown that calculations using the proposed model require less computing resources compared with the standard models of ionic solutions.

Surface tension of different sized single-component droplets, according to macroscopic data obtained using the lattice gas model and the critical droplet size during phase formation

Size dependences of the surface tension of spherical single-component droplets are calculated using equations of the lattice gas model for 19 compounds. Parameters of the model are found from experimental data on the surface tension of these compounds for a macroscopic planar surface. The chosen low-molecular compounds satisfy the law of corresponding states. To improve agreement with the experimental data, Lennard-Jones potential parameters are varied within 10% deviations. The surface tensions of different sized equilibrium droplets are calculated at elevated and lowered temperatures. It is found that the surface tension of droplets grows monotonically as the droplet size increases from zero to its bulk value. The droplet size R 0 corresponding to zero surface tension corresponds to the critical size of the emergence of a new phase. The critical droplet sizes in the new phase of the considered compounds are estimated for the first time.

Interfacial properties and morphological evolution of liquid Ag film on the modified graphene

The interfacial wettability and morphological evolution of liquid on a solid substrate, as natural phenomena, have received great attention in recent years. Although much work has been done to study this process, existing studies mainly focus on the wetting properties of water. Therefore, in this paper, we use molecular dynamics simulation method to study the interfacial phenomena of the nanoscale liquid silver on graphene, whose surface has been modified. By making different comparisons, such as Lennard-Jones (LJ) potential parameters, the surface structures of substrates, the thickness values of films and the shapes of films, the influences of these variables on wetting properties of liquid silver on graphene are studied. The results show that the dewetting of liquid silver occurs on graphene, implying that the wettability of liquid silver is weak, and that the potential parameters, the surface structure of substrates, the thickness of film and the shape of film have great influences on the wettability and morphology evolution of film: the change of these factors can affect the dewetting properties of liquid silver, which is evident by the detachment time and detachment speed. With the increase of LJ potential parameters, the detachment time is larger while the contraction speed and the detachment speed are smaller. Compared with the detachment times on different carbon-based substrates, the detachment time is small on the pillared graphene, followed by the vertical carbon nanotube, and the detachment time is large on the graphene. With increasing the thickness of the film, the detachment time becomes larger. The detachment time of the circle film is smaller than those of the regular hexagon film and square film, manifesting that the films with smooth boundary are beneficial to separating from the substrate. Moreover, by setting a system of two liquid films, we study the formation of silver bridge of two films and the fracture or fusion of the bridge. When two liquid films initially contact each other, the liquid bridge forms. However, the growth behaviors of liquid bridges are different from each other, some liquid bridges become slim and finally fractures, other liquid bridges do not fracture and help two droplets form one bigger drop. These different behaviors mainly depend on the size of film. This study is very valuable for well understanding the superhydrophobic surfaces and the morphological evolutions of Ag films on the graphene. Furthermore, these findings can provide an effective method to control the dewetting behavior of liquid Ag and the fracture or fusion of the two liquid drops by tuning the size of the films.

Corrosion Study of Steels In Liquid Lead-Bismuth Cooled Nuclear Reactors by Computer Simulation using Moldy Code

The corrosion of steel in liquid lead-bismuth has been studied by computer simulation using MOLDY code. The diffusion processes among atoms are assumed to be the key issues to understand the corrosion mechanism microscopically. In order to simulate these diffusion processes, the inter-atomic potential between Fe-Fe, Pb-Pb, Bi-Bi, Cr-Cr and Ni-Ni are assumed to obey the Lennard-Jones potential. The Lennard-Jones potential parameters of above pairs of atom have been derived by fitting the data available in the literature with the Lennard-Jones equation. The initial positions of the system are taken from the crystal structures data including the cell parameters. The simulation cell was a box with the volume 60x30x30 Å3 that were filled by 2864 atoms. Nickel and chromium atoms were substituted into Fe crystal with the percentage 10% and 16 % respectively to construct the systems of SS-316 which contacted by 50%Pb-50%Bi. The molecular dynamic simulations have been carried out for surface interaction between steel crystal with liquid lead-bismuth for several temperatures. After done the above simulation, the simulation is then tried by using 45%Pb-55%Bi (Pb-Bi Eutectic). The results of molecular dynamic simulations for several temperatures and the effect of variation of Pb and Bi above will be presented in this paper.