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

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.

/pdf/electronics-and-optoelectronics-of-two-dimensional-2jbqr1unvw.pdf

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

http://absimage.aps.org/image/MAR12/MWS_MAR12-2011-003206.pdf

Integrated circuits and logic operations with high room temperature voltage gain based on single-layer MoS$_{2}$

Here, we present a numerical post-processing method for removing the effect of anti-symmetric residual aberrations in high-resolution transmission electron microscopy (HRTEM) images of weakly scattering 2D-objects. The method is based on applying the same aberrations with the opposite phase to the Fourier transform of the recorded image intensity and subsequently inverting the Fourier transform. We present the theoretical justification of the method and its verification based on simulated images in the case of low-order anti-symmetric aberrations. Ultimately the method is applied to experimental hardware aberration-corrected HRTEM images of single-layer graphene and MoSe2 resulting in images with strongly reduced residual low-order aberrations, and consequently improved interpretability. Alternatively, this method can be used to estimate by trial and error the residual anti-symmetric aberrations in HRTEM images of weakly scattering objects.

Numerical correction of anti-symmetric aberrations in single HRTEM images

Low-dimensional materials such as graphene are composed of a single layer or at most a few layers of atoms. To resolve the structure of these materials requires an instrument with sub-Angstrom resolution – a regime where the atomic force microscope (AFM) excels. Going beyond simple topography measurements, there are a host of mechanical and electrical characterization techniques that rely on the AFM cantilever being able to literally “feel” the mechanical and electrical properties of the material. In this paper, we describe several new and existing applications where AFM is used to probe the mechanical and electrical properties of these rapidly

Exploring flatland: AFM of mechanical and electrical properties of graphene, MoS 2 and other low-dimensional materials

Devices based on two-dimensional (2D) semiconductors hold promise for the realization of compact and versatile on-chip interconnects between electrical and optical signals. Although light emitting diodes (LEDs) are fundamental building blocks for integrated photonics, the fabrication of light sources made of bulk materials on complementary metal-oxide-semiconductor (CMOS) circuits is challenging. While LEDs based on van der Waals heterostructures have been realized, the control of the emission properties necessary for information processing remains limited. Here, we show room-temperature electrical control of the location, directionality and polarization of light emitted from a 2D LED operating at MHz frequencies. We integrate the LED in a planar cavity to couple the polariton emission angle and polarization to the in-plane exciton momentum, controlled by a lateral voltage. These findings demonstrate the potential of TMDCs as fast, compact and tunable light sources, promising for the realization of electrically driven polariton lasers. 

/pdf/room-temperature-electrical-control-of-polarization-and-2qrotf3i.pdf

Room-temperature electrical control of polarization and emission angle in a cavity-integrated 2D pulsed LED

The design, fabrication, and characterization of wafer‐scale, zero‐bias power detectors based on 2D MoS2 field‐effect transistors (FETs) are demonstrated. The MoS2 FETs are fabricated using a wafer‐scale process on 8 μm‐thick polyimide film, which, in principle, serves as a flexible substrate. The performances of two chemical vapor deposition MoS2 sheets, grown with different processes and showing different thicknesses, are analyzed and compared from the single device fabrication and characterization steps to the circuit level. The power‐detector prototypes exploit the nonlinearity of the transistors above the cut‐off frequency of the devices. The proposed detectors are designed employing a transistor model based on measurement results. The fabricated circuits operate in the Ku‐band between 12 and 18 GHz, with a demonstrated voltage responsivity of 45 V W−1 at 18 GHz in the case of monolayer MoS2 and 104 V W−1 at 16 GHz in the case of multilayer MoS2, both achieved without applied DC bias. They are the best‐performing power detectors fabricated on flexible substrate reported to date. The measured dynamic range exceeds 30 dB, outperforming other semiconductor technologies like silicon complementary metal–oxide–semiconductor circuits and GaAs Schottky diodes.

/pdf/zero-bias-power-detector-circuits-based-on-mos2-field-effect-3br8fl75.pdf

Andras Kis

Papers

Integrated circuits and logic operations with high room temperature voltage gain based on single-layer MoS$_{2}$

Numerical correction of anti-symmetric aberrations in single HRTEM images

Exploring flatland: AFM of mechanical and electrical properties of graphene, MoS 2 and other low-dimensional materials

Room-temperature electrical control of polarization and emission angle in a cavity-integrated 2D pulsed LED

Zero‐Bias Power‐Detector Circuits based on MoS2 Field‐Effect Transistors on Wafer‐Scale Flexible Substrates