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

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

First principles calculations were performed to investigate the structural, elastic, and electronic properties of IrN2 for various space groups: cubic Fm-3m and Pa-3, hexagonal P3(2)21, tetragonal P4(2)/mnm, orthorhombic Pmmn, Pnnm, and Pnn2, and monoclinic P2(1)/c. Our calculation indicates that the P2(1)/c phase with arsenopyrite-type structure is energetically more stable than the other phases. It is semiconducting (the remaining phases are metallic) and contains diatomic N-N with the bond distance of 1.414 A. These characters are consistent with the experimental facts that IrN2 is in lower symmetry and nonmetallic. Our conclusion is also in agreement with the recent theoretical studies that the most stable phase of IrN2 is monoclinic P2(1)/c. The calculated bulk modulus of 373 GPa is also the highest among the considered space groups. It matches the recent theoretical values of 357 GPa within 4.3% and of 402 GPa within 7.8%, but smaller than the experimental value of 428 GPa by 14.7%. Chemical bonding and potential displacive phase transitions are discussed for IrN2. For IrN3, cubic skutterudite structure (Im-3) was assumed.

Crystal structures and elastic properties of superhard IrN2 and IrN3 from first principles

Production, properties and potential of graphene

Topological design and additive manufacturing of porous metals for bone scaffolds and orthopaedic implants: A review.

We review a set of ideas concerning the flexibility of network materials, broadly defined as structures in which atoms form small polyhedral units that are connected at corners. One clear example is represented by the family of silica polymorphs, with structures composed of corner-lined SiO4tetrahedra. TheRigid Unit Mode(RUM) is defined as any normal mode in which the structural polyhedra can translate and/or rotate without distortion, and since forces associated with changing the size and shape of the polyhedra are much stronger than those associated with rotations of two polyhedra around a shared vertex, the RUMs might be expected to have low frequencies compared to all other phonon modes. In this paper we discuss the flexibility of network structures, and how RUMs can arise in such structures, both in principle and in a number of specific examples of real systems. We also discuss applications of the RUM model, particularly for our understanding of phenomena such as displacive phase transitions and negative thermal expansion in network materials. .

The Rigid Unit Mode model: review of ideas and applications.

The compression behavior of Ni77P23 amorphous alloy is investigated at room temperature in a diamond-anvil cell instrument using in-situ high pressure energy dispersive X-ray diffraction with a synchrotron radiation source. The equation of state is determined by fitting the experimental data according to Birch-Murnaghan equation: −ΔV/V0=0.08606P−3.2×10−4P2+5.7×10−6P3. It is found that the structure of Ni77P23 amorphous alloy is stable under pressures up to 30.5 GPa.

Compression behavior and equation of state of Ni77P23 amorphous alloy

In this report, a series of amorphous organic optoelectronic pyrene–fluorene derivative materials (BP1, BP2, PFP1, PFP2, OP1, OP2) were systematically investigated through a theoretical method. The...

Theoretical Exploration of Carrier Dynamics in Amorphous Pyrene-Fluorene Derivative Organic Semiconductors.

Carrier transport in organic semiconductors (OSCs) plays an essential role in device performance. OSCs are generally divided into hole-transporting (p-type) and electron-transporting (n-type) mater...

From Intrinsic Bipolar Transport to the Abnormal Curves of Mobility–E1/2 in the Common Hole-Transporting Materials

The invention discloses a block binary NiP noncrystal alloy and making method, which is characterized by the following: sedimenting noncrystal alloy on the electric sediment mould (12); adopting high-purity activated nickel board (11) as soluble anode to provide nickel ion; designing the shape of noncrystal product for stainless steel board (2) as insoluble cathode; inserting in the electric sediment mould (12); changing plating liquid to change component scale, size.

Gong Li

Papers

The Rigid Unit Mode model: review of ideas and applications.

Compression behavior and equation of state of Ni77P23 amorphous alloy

Theoretical Exploration of Carrier Dynamics in Amorphous Pyrene-Fluorene Derivative Organic Semiconductors.

From Intrinsic Bipolar Transport to the Abnormal Curves of Mobility–E1/2 in the Common Hole-Transporting Materials

Binary NiP amorphous alloy bulk and method for preparing same