Abstract : Simulation and computational methodologies are the third pillar alongside theory and experiment in materials science and engineering. Multiphysics and multiscale modeling and simulations incorporating proper numerical techniques and algorithms are key to understand the fundamental mechanisms in controlling the macroscopic material behaviors and make predictions. The development requires interdisciplinary collaborations and efforts, including applied physics, materials science, solid mechanics and applied mathematics. We propose a minisymposium in three sessions, with the aim of bringing together experts from diverse communities to share recent advances and research highlights in the understanding of this topic from their respective perspectives.
[02135] ESES, a Eulerian and Lagrangian molecular surface generator
Format : Talk at Waseda University
Author(s) :
Weihua Geng (Southern Methodist University)
Abstract : The Poisson-Boltzmann (PB) model is numerically solved either on grid based meshes using finite difference/element methods or on body-fitted meshes using boundary element methods. In this talk, we investigate the distinguished features of the Eulerian Solvent Excluded Surface (ESES) software with which both Eulerian and Lagrangian surfaces are produced. We investigate the performance with these two types of surface discretization usingthe grid based MIBPB solver and body-fitted TABI-PB solvers.
[02756] From nanocrystals to glasses: a strengthening mechanism analysis for amorphization.
Format : Talk at Waseda University
Author(s) :
Chuqi CHEN (Hong Kong University of Science and Technology)
Yang Xiang (Hong Kong University of Science and Technology)
Abstract : Recently, many studies investigated the correlation between the strength of the polycrystals, and the grain size and grain boundary width through both experimental and molecular dynamics simulation approaches. Results reveal that as grain boundary width increases, the crystalline structure of the grain boundary region transforms into an amorphous state. We propose mechanism analysis to elucidate the underlying mechanisms that govern the aforementioned relationships.
[02794] Sum-of-Gaussians method with applications to molecular dynamics simulations
Format : Talk at Waseda University
Author(s) :
Jiuyang Liang (Shanghai Jiao Tong University)
Abstract : Sum-of-Gaussians (SOG) method has attracted attention in many applications. In this talk, we will review some recently-developed SOG methods. Based on a sum-of-Gaussians decomposition of the Coulomb kernel, we develop an accurate, highly efficient, and scalable random batch sum-of-Gaussians (RBSOG) method for molecular dynamics simulations of systems with long-range interactions. Numerical results, including SPC/E bulk water and phase-separated electrolytes, are presented to show the attractive performance of the algorithm, including the superscalability in parallel computing.
[03201] Random-batch Ewald method for molecular dynamics
Format : Talk at Waseda University
Author(s) :
Zhenli Xu (Shanghai Jiao Tong University)
Abstract : We present a random-batch Ewald method for molecular dynamics of particle systems with long-range interactions. It takes advantage of the random minibatch strategy for particles, leading to an order N algorithm. It is based on the Ewald splitting of the Coulomb kernel and the random importance sampling is employed in the Fourier part such that the force variance can be reduced. Numerical results are presented to show the attractive performance of the algorithm.
[04335] Molecular Dynamics Simulation of Concentrated Entangled Polymers in Athermal Solvents
Format : Talk at Waseda University
Author(s) :
Jiayi wang (HKUST)
Abstract : We have developed a coarse-grained model to simulate the geometric and dynamical properties of entangled polymer chains dissolved in athermal solvents. Our model successfully verifies the concentration scaling relationships of the geometric characteristics. In terms of the dynamical aspect, we have discovered that the swelling of the entangled polymer chains in athermal solvents leads to enhanced local chain stiffness or effective system elastic modulus.
[04386] Multiscale modeling and Simulations of Interfacial Defects in based on PN model
Author(s) :
Shuyang Dai (Wuhan University)
Abstract : A multiscale continuum model is developed to describe the defect structures in crystalline material such as FCC metals. The interface structure for twist, tilt and misfit grain boundaries are described by the dislocation network. The model incorporates both the anisotropy elasticity of each grain in crystalline materials and the molecular dynamics calculation informed interaction between two bulks, i.e., the nonlinear generalized stacking-fault energy. The equilibrium structures are obtained from the numerical simulations of the force balance differential equations. We apply this approach to determine the structure and energetics of twist, tilt and general grain boundaries. We also investigated the dislocation structure in heterogeneous crystalline material. Our model agrees well with the atomistic results. An analytical description is developed based on the obtained structural features.
[04817] Solving integral equations on non-smooth boundaries
Format : Talk at Waseda University
Author(s) :
Shidong Jiang (Center for Computational Mathematics, Flatiron Institute, Simons Foundation)
Johan Helsing (Lund University)
Abstract : A numerical scheme is presented for the solution of Fredholm second-kind boundary integral equations on non-smooth boundaries. The scheme, which builds on recursively compressed inverse preconditioning (RCIP), is universal as it is independent of the nature of the singularities. The performance of the scheme is illustrated via several numerical examples.
[05284] A fast algorithm for Dirichlet partition problems
Format : Talk at Waseda University
Author(s) :
Dong Wang (The Chinese University of Hong Kong, Shenzhen)
Abstract : A Dirichlet k-partition of a domain is a collection of k pairwise disjoint open subsets such that the sum of their first Laplace--Dirichlet eigenvalues is minimal. In this talk, we propose a new relaxation of the problem by introducing auxiliary indicator functions of domains and develop a simple and efficient diffusion generated method to compute Dirichlet k-partitions for arbitrary domains. The method only alternates three steps: 1. convolution, 2. thresholding, and 3. projection. The method is simple, easy to implement, insensitive to initial guesses and can be effectively applied to arbitrary domains without any special discretization. At each iteration, the computational complexity is linear in the discretization of the computational domain. Moreover, we theoretically prove the energy decaying property of the method. Experiments are performed to show the accuracy of approximation, efficiency and unconditional stability of the algorithm. We apply the proposed algorithms on both 2- and 3-dimensional flat tori, triangle, square, pentagon, hexagon, disk, three-fold star, five-fold star, cube, ball, and tetrahedron domains to compute Dirichlet k-partitions for different k to show the effectiveness of the proposed method. Compared to previous work with reported computational time, the proposed method achieves hundreds of times acceleration.
