First-principles molecular dynamics (FPMD) simulation is a powerful tool for studying the mechanical, chemical, and thermal properties of materials. However, because of the fundamental time-scale limitation of molecular dynamics and the high computational cost of density functional theory, many of the rare events that dominate these properties cannot be directly investigated. Several methods of accelerating FPMD calculations have been developed to analyze these rare events, but to the best of the authors’ knowledge, no quantitative computation of event rate and activation free energy has been achieved. Here, we have developed an accelerated FPMD based on FPMD and the adaptive boost method (Ishii et al. Phys. Rev. B 85, 064303 (2012)), which remove the fundamental drawback of FPMD: time-scale limitation. We also propose a novel boost potential construction algorithms that allows an accurate boost potential to be constructed with a limited number of FPMD samplings. In this study, to confirm the validity of the method, we compute the diffusion of a Li atom in a Si crystal. The temperature-dependent diffusivity was obtained and the activation enthalpy was calculated from an Arrhenius plot and compared with reported experimental diffusivities.

第一性原理分子动力学（FPMD）模拟是研究材料的机械，化学和热学性质的强大工具。但是，由于分子动力学的基本时标限制和密度泛函理论的高计算成本，支配这些特性的许多罕见事件无法直接研究。已经开发了几种加速FPMD计算的方法来分析这些罕见事件，但据作者所知，尚未实现事件发生率和活化自由能的定量计算。在这里，我们基于FPMD和自适应升压方法开发了一种加速FPMD（Ishii等人，Phys。Rev. B 85（064303（2012）），其消除了FPMD的基本缺点：时标限制。我们还提出了一种新颖的升压电位构建算法，该算法允许使用有限数量的FPMD采样来构建准确的升压电位。在这项研究中，为证实该方法的有效性，我们计算了Li原子在Si晶体中的扩散。获得了随温度变化的扩散率，并根据Arrhenius图计算了激活焓，并将其与报告的实验扩散率进行了比较。