Diffusion of interstitial alloying elements like H, O, C, and N in metals and their continuous relocation and interactions with their microstructures have crucial influences on metals properties. However, besides limitations in experimental tools in capturing these mechanisms, the inefficiency of numerical tools also inhibits modeling efforts. Here, we present an efficient framework to perform hybrid grand canonical Monte Carlo and molecular dynamics simulations that allow for parallel insertion/deletion of Monte Carlo moves. A new methodology for calculation of the energy difference at trial moves that can be applied to many-body potentials as well as pair ones is a primary feature of our implementation. We study H diffusion in Fe (ferrite phase) and Ni polycrystalline samples to demonstrate the efficiency and scalability of the algorithm and its application. The computational cost of using our framework for half a million atoms is a factor of 250 less than the cost of using existing libraries.
Grand-Canonical Quantized Liquid Density-Functional Theory in a Car-Parrinello Implementation
量子化液体密度泛函理论[Phys. Rev. E 2009，80，031603]是一种开发用于评估多孔纳米材料中气体分子吸附的方法，在巨正则系综内重新制定。有了巨势，就有可能直接比较外部和内部的热力学量。在我们的新的实施方案中，利用汽车Parrinello的方法，并给出了，特别是低温模拟，一个显着的计算优势，在原来的规范的方法。对原始QLDFT的方法进行了验证，并应用于模型电位和石墨狭缝孔。
Ab-initio molecular dynamics simulation of hydrogen diffusion in $α$-iron
采用第一性原理原子分子动力学模拟，在微正则系综和正则系综下研究了间隙氢在$α$ -铁中的扩散。$θ=1/16 and 1/2 have been considered by locating interstitial hydrogen atoms at random positions in a $ 2 \times 2 \times 2$超晶胞之间的氢与铁比率。我们发现，平均最佳吸收位置和扩散势垒依赖于interestial的浓度。铁的德拜温度随间隙氢浓度的增加而单调下降，证明了大量扩散氢原子的存在显著削弱了铁-铁原子间相互作用势。
