Utimula Keishu, Ichibha Tom, Prayogo Genki I, Hongo Kenta, Nakano Kousuke, Maezono Ryo
School of Materials Science, JAIST, Asahidai 1-1, Nomi, Ishikawa, 923-1292, Japan.
School of Information Science, JAIST, Asahidai 1-1, Nomi, Ishikawa, 923-1292, Japan.
Sci Rep. 2021 Mar 31;11(1):7261. doi: 10.1038/s41598-021-86274-3.
We have developed a framework for using quantum annealing computation to evaluate a key quantity in ionic diffusion in solids, the correlation factor. Existing methods can only calculate the correlation factor analytically in the case of physically unrealistic models, making it difficult to relate microstructural information about diffusion path networks obtainable by current ab initio techniques to macroscopic quantities such as diffusion coefficients. We have mapped the problem into a quantum spin system described by the Ising Hamiltonian. By applying our framework in combination with ab initio technique, it is possible to understand how diffusion coefficients are controlled by temperatures, pressures, atomic substitutions, and other factors. We have calculated the correlation factor in a simple case with a known exact result by a variety of computational methods, including simulated quantum annealing on the spin models, the classical random walk, the matrix description, and quantum annealing on D-Wave with hybrid solver . This comparison shows that all the evaluations give consistent results with each other, but that many of the conventional approaches require infeasible computational costs. Quantum annealing is also currently infeasible because of the cost and scarcity of qubits, but we argue that when technological advances alter this situation, quantum annealing will easily outperform all existing methods.
我们已经开发出一种框架，用于利用量子退火计算来评估固体中离子扩散的一个关键量——关联因子。现有的方法仅能在物理上不现实的模型情况下解析计算关联因子，这使得难以将通过当前从头算技术获得的关于扩散路径网络的微观结构信息与诸如扩散系数等宏观量联系起来。我们已将该问题映射到一个由伊辛哈密顿量描述的量子自旋系统中。通过将我们的框架与从头算技术相结合应用，就有可能理解扩散系数是如何受温度、压力、原子取代及其他因素控制的。我们已经通过多种计算方法在一个具有已知精确结果的简单情形中计算了关联因子，这些方法包括自旋模型上的模拟量子退火、经典随机游走、矩阵描述以及使用混合求解器在D-Wave上进行量子退火。这种比较表明，所有评估结果相互一致，但许多传统方法需要难以承受的计算成本。由于量子比特的成本和稀缺性，目前量子退火也不可行，但我们认为当技术进步改变这种情况时，量子退火将轻松超越所有现有方法。
