arXiv subjects

Hong An

Publications and source records attributed to Hong An.

23 records · Page 2Linked to original sources

arXiv2020

Extreme-Scale Density Functional Theory High Performance Computing of DGDFT for Tens of Thousands of Atoms using Millions of Cores on Sunway TaihuLight

High performance computing (HPC) is a powerful tool to accelerate the Kohn-Sham density functional theory (KS-DFT) calculations on modern heterogeneous supercomputers. Here, we describe a massively extreme-scale parallel and portable implementation of discontinuous Galerkin density functional theory (DGDFT) method on the Sunway TaihuLight supercomputer. The DGDFT method uses the adaptive local basis (ALB) functions generated on-the-fly during the self-consistent field (SCF) iteration to solve the KS equations with the high precision comparable to that of plane-wave basis set. In particular, the DGDFT method adopts a two-level parallelization strategy that makes use of different types of data distribution, task scheduling, and data communication schemes, and combines with the feature of master-slave multi-thread heterogeneous parallelism of SW26010 processor, resulting in extreme-scale HPC KS-DFT calculations on the Sunway TaihuLight supercomputer. We show that the DGDFT method can scale up to 8,519,680 processing cores (131,072 core groups) on the Sunway TaihuLight supercomputer for investigating the electronic structures of two-dimensional (2D) metallic graphene systems containing tens of thousands of carbon atoms.

physics.comp-ph↗

arXiv2019

Reply to comments on "Gapless spin liquid ground state of spin-1/2 $J_1$-$J_2$ Heisenberg model on square lattices"

In a recent comments [arXiv:1909.12788 (2019)], Zhao et al. argue that the definition of dimer orders used in our paper [Phys. Rev. B 98, 241109 (2018)] may not rule out valence bond solid (VBS) orders of $J_1$-$J_2$ model on the open boundary conditions (OBC). In this reply, we show that their argument does not apply to our case.

cond-mat.str-el↗

arXiv2018

Gapless spin liquid ground state of spin-1/2 $J_1$-$J_2$ Heisenberg model on square lattices

The spin-1/2 $J_1$-$J_2$ Heisenberg model on square lattices are investigated via the finite projected entangled pair states (PEPS) method. Using the recently developed gradient optimization method combining with Monte Carlo sampling techniques, we are able to obtain the ground states energies that are competitive to the best results. The calculations show that there is no Néel order, dimer order and plaquette order in the region of 0.42 $\lesssim J_2/J_1\lesssim$ 0.6, suggesting a single spin liquid phase in the intermediate region. Furthermore, the calculated staggered spin, dimer and plaquette correlation functions all have power law decay behaviours, which provide strong evidences that the intermediate nonmagnetic phase is a single gapless spin liquid state.

cond-mat.str-el↗

arXiv2018

PEPS++: Towards Extreme-scale Simulations of Strongly Correlated Quantum Many-particle Models on Sunway TainhuLight

The study of strongly frustrated magnetic systems has drawn great attentions from both theoretical and experimental physics. Efficient simulations of these models are essential for understanding their exotic properties. Here we present PEPS++, a novel computational paradigm for simulating frustrated magnetic systems and other strongly correlated quantum many-body systems. PEPS++ can accurately solve these models at the extreme scale with low cost and high scalability on modern heterogeneous supercomputers. We implement PEPS++ on Sunway TaihuLight based on a carefully designed tensor computation library for manipulating high-rank tensors and optimize it by invoking various high-performance matrix and tensor operations. By solving a 2D strongly frustrated $J_1$-$J_2$ model with over ten million cores, PEPS++ demonstrates the capability of simulating strongly correlated quantum many-body problems at unprecedented scales with accuracy and time-to-solution far beyond the previous state of the art.

cond-mat.str-el↗

arXiv2013

Phase-Priority based Directory Coherence for Multicore Processor

As the number of cores in a single chip increases, a typical implementation of coherence protocol adds significant hardware and complexity overhead. Besides, the performance of CMP system depends on the data access latency, which is highly affected by coherence protocol and on-chip interconnect. In this paper, we propose PPB (Phase-Priority Based) cache coherence protocol, an optimization of modern directory coherence protocol. We take advantage of the observation that transient states occur in directory coherence protocol, resulting in some unnecessary transient states and stalling. PPB cache coherence protocol decouples a coherence transaction and introduces the idea of phase message. This phase is considered as the priority of the message. Additionally, we also add new priority-based arbitrators in on-chip network to support PPB cache coherence protocol. This mechanism in on-chip network can support effective cache access, which makes the on-chip network more efficient. Our analysis on an execution-driven full system simulator using SPLASH-2 benchmark shows that PPB cache coherence outperforms a MESI based directory, and the number of unnecessary transient states and stalling reduces up to 24%. Also it reported the speedup of 7.4%. Other advantages of this strategy are reduced delay of flits and significantly less energy consumption in on-chip network.

cs.AR↗