论文标题

精确地通过不可还原衍生物计算声子

Precisely computing phonons via irreducible derivatives

论文作者

Bandi, Sasaank, Marianetti, C. A.

论文摘要

通常认为来自第一原理的计算声子被认为是解决问题的问题,但是现有技术的不足仍然会在具有敏感声子的系统中产生不足的结果。在这里,我们使用孤独的不可衍生物(LID)和捆绑的不可减至的衍生化(BID)方法来避免此问题,以通过有限位移来计算声子,其中前者通过能量衍生物优化了精度,而后者则使用力衍生物提供了最有效的算法。得出了出价的条件数(CNO)基础,以确保误差的最小扩增。此外,制定了混合盖出价方法,其中选择了使用盖子计算的选择不可约的衍生物。我们说明了具有敏感声子的两个原型系统的方法:形状内存合金AUZN和金属锂。将上述晶体中所产生的声子与文献中的计算进行比较,揭示了非平凡的不准确性。我们的方法可以完全自动化,这使得它们非常适合感兴趣的利基系统和高通量方法。

Computing phonons from first-principles is typically considered a solved problem, yet inadequacies in existing techniques continue to yield deficient results in systems with sensitive phonons. Here we circumvent this issue using the lone irreducible derivative (LID) and bundled irreducible derivative (BID) approaches to computing phonons via finite displacements, where the former optimizes precision via energy derivatives and the latter provides the most efficient algorithm using force derivatives. A condition number optimized (CNO) basis for BID is derived which guarantees the minimum amplification of error. Additionally, a hybrid LID-BID approach is formulated, where select irreducible derivatives computed using LID replace BID results. We illustrate our approach on two prototypical systems with sensitive phonons: the shape memory alloy AuZn and metallic lithium. Comparing our resulting phonons in the aforementioned crystals to calculations in the literature reveals nontrivial inaccuracies. Our approaches can be fully automated, making them well suited for both niche systems of interest and high throughput approaches.

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