Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

Hexagonal boron nitride monolayers on metal supports: Versatile templates for atoms, molecules and nanostructures

Effects of carbon additives on the properties of ZrB2–based composites: A review

Microwave synthesis and characterization of Zn-doped nickel ferrite nanoparticles

Structural and magnetic properties of nano-crystalline Ni–Zn ferrites synthesized using egg-white precursor

Mechanical properties of defective hybrid graphene-boron nitride nanosheets: A molecular dynamics study

Nanocrystalline Ni 1− x Zn x Fe 2 O 4 ( x =0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1) ferrite was produced by high energy ball milling of ZnO, NiO and Fe 2 O 3 powder mixtures. X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM) were carried out to investigate structural, chemical and magnetic aspects of Ni–Zn ferrite. Ni 1− x Zn x Fe 2 O 4 appeared to form in two stages involving formation of Zn ferrite by faster diffusion of ZnO in Fe 2 O 3 followed by diffusion of NiO in Zn ferrite to form Ni–Zn ferrite. The crystallite size of final product after 60 h of ball milling for all samples was found to be ∼18 nm independent of composition. It was found that the magnetization value of Ni 1− x Zn x Fe 2 O 4 initially increases and then decreases as Zn content increases with a maximum value of 83.2 emu/g at x =0.5. The coercivity value of Ni 1− x Zn x Fe 2 O 4 decreases steadily with increasing Zn content.

Effect of composition on structural and magnetic properties of nanocrystalline ball milled ni1-xznxfe2o4 ferrite

Mechanosynthesis of nanostructured magnetic Ni–Zn ferrite

Preparation of nanocrystalline ZrB2–based powder by aluminothermic and magnesiothermic reductions in M/ZrO2/B2O3 (M = Al or Mg) systems was investigated. In this research, high energy ball milling was employed to persuade necessary conditions for the occurrence of a mechanically induced self-sustaining reaction (MSR). The course of MSR reactions were recorded by a noticeable pressure rise in the system during milling. Ignition times for ZrB2 formation by aluminothermic and magnesiothermic reductions were found to be 13 and 6 min, respectively. Zirconium diboride formation mechanism in both systems was explained through the analysis of the relevant sub-reactions.

https://digital.csic.es/bitstream/10261/104193/1/AdvApplCeram%2878%29.pdf

Mechanosynthesis of nanocrystalline ZrB2-based powders by mechanically induced self-sustaining reaction method

The ternary compound boron carbonitride (BCN) was synthesized in the form of few-layer nanosheets through a mechanically induced self-sustaining reaction (MSR). Magnesium was used to reduce boron trioxide in the presence of melamine in a combustive manner. The process to form the nanostructured material was very rapid (less than 40 min). The prepared powder was investigated by various techniques such as X-ray diffraction (XRD), Fourier Transform infrared (FTIR), Micro-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), and electron energy loss spectroscopy (EELS). The thermal stability and the optical behavior of the BCN nanosheets were also studied by thermal analysis and UV-vis spectroscopy, respectively. The formation mechanism of the nanosheet morphology was described in detail.

/pdf/a-novel-simple-and-rapid-route-to-the-synthesis-of-boron-3756asmp08.pdf

Maisam Jalaly

Papers

Mechanical properties of defective hybrid graphene-boron nitride nanosheets: A molecular dynamics study

Effect of composition on structural and magnetic properties of nanocrystalline ball milled ni1-xznxfe2o4 ferrite

Mechanosynthesis of nanostructured magnetic Ni–Zn ferrite

Mechanosynthesis of nanocrystalline ZrB2-based powders by mechanically induced self-sustaining reaction method

A novel, simple and rapid route to the synthesis of boron cabonitride nanosheets: combustive gaseous unfolding