A quantum fluid of metallic hydrogen suggested by first-principles calculations
A quantum fluid of metallic hydrogen suggested by first-principles calculations
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DOI：
10.1038/nature02968
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发表时间：
2004-10-07
期刊：
影响因子：
64.8
通讯作者：
Galli, G
中科院分区：
文献类型：
--
作者：
Bonev, SA;Schwegler, E;Galli, G
一般假定(1-3)，在足够高的压力下，固态氢会转变为类碱金属晶体。然而，一些理论模型(4，5)也表明，压缩氢在低温下可能形成一种不寻常的双组分(质子和电子)金属流体，甚至可能形成零温度液体基态。这些新的物质状态的存在取决于熔化温度-压力曲线(‘熔化线’)中是否存在最大值。以前对高达44 Gpa压力的氢熔线的测量(6-8)导致了关于这一最大值的存在的争议结论。在这里，我们报告从头计算，建立了高达200 Gpa的熔融线。我们预测，分子间相互作用的细微变化会导致熔融线下降到90 Gpa以上。这意味着，当固体分子氢被压缩时，它在变成单原子晶体之前会转化为低温量子流体。新出现的氢及其同位素的低温相图与人们熟悉的He-3和He-4(唯一已知的零温液体)相类似，但长程库仑相互作用和氢中存在的大组分质量比将导致显著不同的性质[9]。
It is generally assumed(1-3) that solid hydrogen will transform into a metallic alkali-like crystal at sufficiently high pressure. However, some theoretical models(4,5) have also suggested that compressed hydrogen may form an unusual two-component (protons and electrons) metallic fluid at low temperature, or possibly even a zero-temperature liquid ground state. The existence of these new states of matter is conditional on the presence of a maximum in the melting temperature versus pressure curve (the 'melt line'). Previous measurements(6-8) of the hydrogen melt line up to pressures of 44 GPa have led to controversial conclusions regarding the existence of this maximum. Here we report ab initio calculations that establish the melt line up to 200 GPa. We predict that subtle changes in the intermolecular interactions lead to a decline of the melt line above 90 GPa. The implication is that as solid molecular hydrogen is compressed, it transforms into a low-temperature quantum fluid before becoming a monatomic crystal. The emerging low-temperature phase diagram of hydrogen and its isotopes bears analogies with the familiar phases of He-3 and He-4 (the only known zero-temperature liquids), but the long-range Coulomb interactions and the large component mass ratio present in hydrogen would result in dramatically different properties(9).