arXiv subjects

Wanqi Qiu

Publications and source records attributed to Wanqi Qiu.

4 recordsLinked to original sources

arXiv2020

Double lattice potential for molecular dynamics simulation of silicon with demonstrated validity

To reproduce the diamond structure of silicon, double lattice (DL) potential constructed from two interatomic potentials for face centered cubic (fcc) lattice, is proposed for molecular dynamics (MD) simulations. For the validity test of MD simulation, the Tersoff potential, the Stillinger and Weber (SW) potential, the environment-dependent interatomic (EDI) potential, the charge optimized many-body (COMB) potential, and the modified embedded-atom (MEAM) potential have been also employed for comparison. The crystal lattice of simulated silicon system is identified by calculating the distribution functions of the distances between the atoms and the angles between the lines linking an atom with its nearest neighbors. The results are also compared with the perfect silicon crystal. The crystal lattice, the crystallization temperature, and elastic constants have been calculated from MD simulations using above potentials. The results show that the systems with modified Tersoff, SW, EDI, COMB, and MEAM potentials could not exhibit the diamond structure and only the DL potential gives diamond lattice. The ground state for DL potential is the wurtzite structure, and the metastable state formed during rapid cooling is the cubic diamond structure. The physical parameters obtained from the simulation with DL potential are in agreement with the experiment results. This work indicated that only DL potential is valid for MD simulation of silicon crystal among above various potentials.

cond-mat.mtrl-sci↗

arXiv2018

Designing ABO3 crystal structure with Lennard-Jones interatomic potentials

In this paper, our goal is to design ABO3 crystal structure with simple interatomic Lennard-Jones (LJ) potentials and without setting any initial Bravais lattice and it is carried out by molecular dynamics (MD) simulation. In the simulation, the equilibrium distances between atoms are determined by LJ potentials. For the identification of the microstructure of simulated system, we have calculated the distribution functions of both the angles between one atom and its nearest neighbors and the distances between atoms and compared the results with those of ideal lattices. The results have clearly shown that we have successfully produced ABO3 crystal structure by MD simulation.

cond-mat.mtrl-sci↗

arXiv2018

Lennard-Jones interatomic potentials for the allotropes of carbon

Finding appropriate interatomic potentials which can accurately describe the crystal structure of material is one of important topics in material science. In this paper, several interatomic potentials which comprise of Lennard-Jones (LJ) potentials have been proposed for describing both the crystal structures and the evolution of microstructure of the allotropes of carbon such as diamond and graphite. The validity of these LJ potentials can be checked by molecular dynamics (MD) simulation. For the lattice identification of simulated systems, we have calculated the distribution functions of the angles between one atom and its nearest neighbors and the distances between atoms and checked the atomic arrangements. Our simulated results have clearly demonstrated that we have successfully produced diamond and graphite structures by MD simulations and with the above LJ potentials.

cond-mat.mtrl-sci↗

arXiv2018

Crystallization and non-crystallization of Lennard-Jones particles studied by molecular dynamics simulation

What lattice Lennard-Jones (LJ) solid favors, the lattice identification of simulated system and the microstructures of liquid and non-crystalline solid are three important questions in condensed physics and material science and are addressed in this paper. Both the crystallization and non-crystallization of LJ particles have been investigated by molecular dynamic (MD) simulation without setting any initial Bravais lattice. To identify the Bravais lattice of simulated system, two distribution functions of both the angles between one particle and its nearest neighbors and the distances between particles have been proposed. The final identification can be made by comparing these two calculated distribution functions with those of ideal Bravais lattices and checking the particle arrangement of simulated system. Our results have shown that simulated systems show either the face-centered cubic (fcc) lattice or the hexagonal close-packed (hcp) lattice. The microstructure of non-crystalline system is similar to that of LJ liquid at a temperature near the crystallization temperature, and shows no order of the second nearest neighbors in comparison with that of crystalline system. This paper has proposed a new way of investigating the microstructure of material and its evolution, and paved the way for MD simulation of large scale particle system consisting of more than one million particles.

cond-mat.mtrl-sci↗