Last update Sep 16, 2009.  
Here is some results of our numerical simulations. 

The application of the atomisticbased boundary element method to fracture. The system under consideration consists of 20 cracks. Each layer contains 1/4 billion atoms. The height and width of the system is 1.35 micron. Therefore, fractures on the micron scale can be considered. The ABEM method, however, significantly reduces the dimension of the problem. The simulation was done on a single processor. The top figure is a closeup view of some of the cracks.The colors highlights the concentration of the strain. This demonstrates the reduction of the full atomistic (10^(10) m) model to micron scale (10^(6)m). It is a joint work with Xiaojie Wu (2015). 


A nanotube under compression. This recent work aimed to find the fundamental mechnism behind this structural change and how it depends on the loading rate. 

The memory kernels of generalized Langevin equations computed from Krylov subspace methods. The protein 1dif is separated into blocks with each amino ascid as one block. Each block is consider rigid, and only translation and rotation are allowed. With this subspace, with nonoverlapping basis functions, we generate a block Krylov subspace using Lanczos method, and approximate the memory function (Chen, Li, and Liu, J Chem Phys. 2014). 

The bifurcation diagram for the crack in bcc iron. For dynamics models with damping, the system usually follows the stable branches of the bifurcation diagram. Beyond the bifurcation points, however, the system exibit delays, which depends on the strain rate. 

The simulation of a brittle crack in Ironalpha with rigid BC. Fixing the positions of the atoms at the boundary produce a great amount of reflection, which later will alter the crack speed. 

The simulation of a brittle crack with absorbing BC. In this case, the boundary reflection has been minimized, and the results agree well with a simulation on a much larger sample. 

The simulation of an edge dislocation in Ironalpha with rigid BC. Fixing the positions of the atoms at the boundary produce a great amount of reflection, which later will affect the propagation of the dislocation core. 

The simulation of an edge dislocation with absorbing BC. In this case, the boundary reflection has been minimized, and the results agree well with a simulation on a much larger sample. 

The simulation of an edge dislocation with absorbing BC. In this case, the boundary reflection has been minimized, and the results agree well with a simulation on a much larger sample. 