金属元素镁高压属性的第一性原理研究

First-principles study of the high pressure properties of elemental magnesium

通过第一性原理计算方法,研究了金属元素镁在高压下的电子属性。电子性质的计算指出,镁的三个高压结构体心立方(bcc)、面心立方(fcc)和简单六角(sh)都是金属相结构,但其金属性比常压结构六角密堆(hcp)弱;通过与镁常压电子结构比较可知,d带贡献的增加以及p-d杂化的增强可能是高压下镁金属性降低的一个原因。镁高压fcc和sh结构的电子局域函数(ELF)通过与常压hcp结构以及高压fcc、sh结构的ELF比较,发现镁的这两个高压结构的价电子被高度排挤到晶格间隙区域,这一特殊现象与其他碱金属和碱土金属元素锂、钠、钾以及钙相似。

The high pressure properties of elemental magnesium（Mg） have been studied by first-principles methods.The body-centered cubic（bcc）,face-centered cubic（fcc） and simple hexagonal（sh） structures are all metallic,but the metallicity is weaker than in the ambient-pressure hexagonal close-packed（hcp） structure.The calculated electronic densities of states（DOS） for Mg at different pressures indicated that the weakening of metallicity can be attributed to the rise of 3d band energy relative to that of the the 3p band and the increased p-d hybridization upon compression.Comparison of the electron localization functions（ELF） of the ambient pressure hcp structure and high pressure fcc and sh structures indicated that the valence electrons in the latter polymorphs are mostly localized in the interstitial sites;this phenomenon is similar to that observed for other alkali and other alkaline-earth metals,such as Li,Na,K and Ca.