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Predicting Thermal Conductivity of Metallic Glasses and Their Nanocomposites
Published in Sumit Sharma, Metallic Glass–Based Nanocomposites, 2019
The initial step before the prediction of thermal conductivity of metallic glass is the creation of its simulation model. Figure 4.10 shows the methodology adapted for performing MD simulation. Material Studio is one such commercial computational code utilized for molecular dynamics (MD) simulation and estimating its properties. MD simulations were performed, where Condensed-stage Optimized Molecular Potentials were utilized for Atomistic Simulation Studies (COMPASS). The COMPASS force field consists of terms for bonds (b), angles (θ), dihedrals (ϕ), out-of-plane angles (χ) as well as cross-terms and two nonbonded functions, a Coulombic function for electrostatic interactions and a 9–6 Lennard–Jones potential for van der Waals interactions. () ETotal=Eb+Eθ+Eϕ+Eχ+Eb,b′+Eb,θ+Eθ,θ′+Eθ,θ′,ϕ+Eq+EvdW
Capture performance and quantum chemistry simulation of composite collectors for coal gasification coarse slag
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Zhonghua Xue, Pengbo Zhao, Chongyi Yang, Lianping Dong, Weiren Bao, Jiancheng Wang, Panpan Fan
Molecular dynamics simulations: Molecular dynamics simulations were performed using Materials Studio 2019 software (MS) to construct and optimize the molecular models of RC, kerosene (n-dodecane), and AK (n-dodecane: AC1202 = 1:1 mass ratio). The simulation box size was 45 × 45 × 140 Å. The one of it has a thickness of 100 Å for the vacuum layer and was simulated with 16 reagent molecules. The RC has a graphite structure with a surface containing functional groups of methyl (−CH), carboxyl (−COOH), hydroxyl (−OH), carboxyl (-C=O), and ether bonds (C-O-C). Then, utilizing graphene (001), the RC model was built, and the functional group ratios were obtained from the XPS results of the RC. The simulations were carried out in the forcite module with the assistance of the COMPASS force field and NVT system. Distributed the charge before the simulation started. The temperature of the whole simulated system was kept stable at 298K. The total time of the simulation was 500 ps, where the time of each step was 1 fs. The Ewald summation method and the atom-based method, respectively, were used to calculate the electrostatic forces and van der Waals forces.
Influence of curing agent ratio, asphalt content and crosslinking degree on the compatibility and component distribution of epoxy asphalt in compound curing agent system
Published in International Journal of Pavement Engineering, 2022
Mingyue Li, Zhaohui Min, Qichang Wang, Wei Huang, Zhiyong Shi
In this study, molecular dynamics simulations were carried out based on Materials studio software. To describe the potential energy of the molecular system accurately, the consistent force field COMPASSII was employed. COMPASSII is suitable for covalent molecular systems, where the valence parameters and atomic point charges are obtained by fitting the ab initio data, and the van der Waals parameters are obtained by fitting the measured cohesive energy density and equilibrium density data (Sun 1995, 1998). Several researchers’ studies have verified that COMPASSII could predict the structure, conformation, frequency, and thermophysical properties of the system accurately and rapidly (Du et al. 2021). ReaxFF is a reaction force field based on the bond order, atoms are set as the basic unit of the simulation, and the interatomic potential is used to describe the reaction in the form of bond order, where the bond order is empirically calculated from the distance between atoms (Shishehbor et al. 2018, 2019). The ReaXFF force field serves the Lammps simulation software. Therefore, due to the limitation of the simulation software, the COMPASSII was used in this paper instead of the ReaXFF.
A milliseconds flash joule heating method for the regeneration of spent cathode carbon
Published in Journal of Environmental Science and Health, Part A, 2022
Pengfei Huang, Rongtao Zhu, Xinxi Zhang, Wenjun Zhang
All molecular dynamics simulations used in this study were performed by the Materials Studio simulation package (accelrys software). From Table 1, it can be known that more than 90% of the elements in the waste cathode carbon are composed of C, F, and Na. Among them, the C element is mainly composed of aromatic compounds in the graphite phase; F and Na are mainly composed of NaF. The system was set to graphite layer and NaF layer to simulate the diffusion of NaF in the graphite layer. The initial configuration was C588F128Na128, consisting of six layers of graphite flakes and four layers of NaF (a = 18.00 Å, b = 18.00 Å, c = 29.00 Å), and periodic boundary conditions were applied in all directions. Based on the constructed system, the compass potential field and the atomic group-based “Group-based” system were selected to calculate the interaction force. “Atom-Based” module and “Ewald” module were chosen to calculate van der Waals force and electrostatic force between particles.