发表机构
University of Zürich; Scuola Internazionale Superiore di Studi Avanzati (SISSA); University of Cambridge; Tohoku University（苏黎世大学; 国际高等研究院; 剑桥大学; 东北大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过第一性原理搜索发现，致密二维氢在中间压力区间可能具有无序基态，其焓低于晶体候选结构，为研究结晶与无序竞争提供了新平台。
AI 中文摘要
高压下的氢是一个极其复杂的体系，具有分子解离、金属化和异常熔化等特征。虽然块体氢已被研究了近一个世纪，但其二维对应物仍未得到探索。通过使用包含多达512个原子的超胞进行第一性原理结构搜索和弛豫，我们确定了致密二维氢的基态结构，在模拟长度尺度上未显示长程晶体有序的证据。在密度泛函理论框架内，这些结构在分子晶体和原子晶体之间的中间压力区间内，其焓低于所有考虑的晶体候选结构。这种偏好已在经典核条件下出现，并随着超胞尺寸的增加而持续存在，而主要结构因子峰的增长速度明显慢于晶体参考相。尽管无法严格排除具有非常大原胞的晶体，但这些发现支持无序基态的可能性，并将致密二维氢确定为研究结晶与结构无序之间竞争的有前景的体系。
英文摘要
Hydrogen under pressure is an extremely complex system featuring molecular dissociation, metallization, and anomalous melting. While bulk hydrogen has been studied for nearly a century, its two-dimensional counterpart remains unexplored. Using first-principles structural searches and relaxations in supercells containing up to 512 atoms, we identify ground-state structures of dense two-dimensional hydrogen showing no evidence of long-range crystalline order over the simulated length scales. Within density functional theory, these structures have lower enthalpy than all crystalline candidates considered over an intermediate pressure interval between molecular and atomic crystals. This preference already emerges with classical nuclei and persists as the supercell size increases, while the dominant structure-factor peaks grow substantially more slowly than in the crystalline reference phases. Although crystals with very large primitive cells cannot be rigorously excluded, these findings support the possibility of a disordered ground state and identify dense two-dimensional hydrogen as a promising setting for investigating competition between crystallization and structural disorder.
