10,136 research outputs found
86 PFLOPS Deep Potential Molecular Dynamics simulation of 100 million atoms with ab initio accuracy
We present the GPU version of DeePMD-kit, which, upon training a deep neural
network model using ab initio data, can drive extremely large-scale molecular
dynamics (MD) simulation with ab initio accuracy. Our tests show that the GPU
version is 7 times faster than the CPU version with the same power consumption.
The code can scale up to the entire Summit supercomputer. For a copper system
of 113, 246, 208 atoms, the code can perform one nanosecond MD simulation per
day, reaching a peak performance of 86 PFLOPS (43% of the peak). Such
unprecedented ability to perform MD simulation with ab initio accuracy opens up
the possibility of studying many important issues in materials and molecules,
such as heterogeneous catalysis, electrochemical cells, irradiation damage,
crack propagation, and biochemical reactions.Comment: 29 pages, 11 figure
Interplay between Quantum Size Effect and Strain Effect on Growth of Nanoscale Metal Thin Film
We develop a theoretical framework to investigate the interplay between
quantum size effect (QSE) and strain effect on the stability of metal
nanofilms. The QSE and strain effect are shown to be coupled through the
concept of "quantum electronic stress. First-principles calculations reveal
large quantum oscillations in the surface stress of metal nanofilms as a
function of film thickness. This adds extrinsically additional strain-coupled
quantum oscillations to surface energy of strained metal nanofilms. Our theory
enables a quantitative estimation of the amount of strain in experimental
samples, and suggests strain be an important factor contributing to the
discrepancies between the existing theories and experiments
Experimental and numerical studies on multi-spherical sliding friction isolation bearing
An innovative multi-spherical sliding friction isolation (MSFI) bearing has recently been developed. The novel isolator has efficient energy dissipation capacity and enough displacement capacity under strong earthquake excitations. The MSFI bearing is completely passive devices, yet shows smart stiffness and smart damping under external excitation. The principles of operation and force-displacement relationship of the novel isolator are presented in this paper. The sliding order of all sliding surfaces and force-displacement hysteretic relationship are verified through a displacement-control testing program, and numerical analysis of the MSFI bearing under low cyclic loading is carried out based on ABAQUS program. The results show the sliding order and force-displacement relationship of the MSFI bearing derived from theoretical analysis results and numerical simulation results are well agree with experimental data which the compression-shear testing of the MSFI bearing specimen with the identical curvature radii and friction coefficients. The adaptive behavior of MSFI bearing permits the isolation system to be separately optimized for multiple levels of seismic intensity and ground motions
catena-Poly[[(4-aminobenzoato)aquasilver(I)]-μ-hexamethylenetetramine]
In the title coordination polymer, [Ag(C7H6NO2)(C6H12N4)(H2O)]n, the AgI ion is five-coordinated by two carboxylate O atoms from one 4-aminobenzoate anion (L), two N atoms from two different hexamethylenetetramine (hmt) ligands, and one water O atom in a distorted square-pyramidal geometry. The metal atom lies on a mirror plane and the L anion, hmt ligand and water molecule all lie across crystallographic mirror planes. Each hmt ligand bridges two neighboring AgI ions, resulting in the formation of a chain structure along the b axis. The chains are linked into a three-dimensional framework by N—H⋯O and O—H⋯O hydrogen bonds
4-Amino-3,5-dichlorobenzenesulfonamide
In the title compound, C6H6Cl2N2O2S, the O atoms of the sulfonamide group lie on one side of the benzene ring and the amino group lies on the opposite side. An intermolecular N—H⋯Cl interaction occurs. In the crystal, adjacent molecules are linked by N—H⋯O hydrogen bonds, forming a three-dimensional structure with supporting π–π stacking interactions [centroid–centroid distance = 3.7903 (12) Å]. A short Cl⋯Cl contact [3.3177 (10) Å] also occurs
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