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寂寞倾城

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[交流] 英语翻译

The structure of the Ta3N5 phase stritantalum pentanitrided is displayed in Figs.2（a） and 2（b）. Each Ta atom is surrounded by six N atoms, and the N atoms are threefold and fourfold Ta coordinated.The optimized volume is found to be just 0.1% smaller than experiment. There are 32 atoms in the unit cell. The corresponding DOS [Fig. 2(c)](Ref. 10) shows that the material is insulating—i.e., a semiconductor with a band gap of 1.5 eV. We note that in reality the band gap will be larger due to the well-known underestimation of the LDA. A more accurate description of the band gap could be obtained by performing quasiparticle calculations using the GW approximation to the self energy,screened-exchange (SX) LDA, self-interaction corrected (SIC), or exact-exchange calculations.
We turn now to the hexagonal phases. The atomic geometry of Ta5N6 is depicted in Figs. 2(d) and 2(e). The closepacked N layers follow the stacking sequence ABAC with Ta atoms and tantalum vacancies in the octahedral holes. The
calculated equilibrium volume is 2.6% smaller than experiment. There are 22 atoms in the unit cell. The DOS shows that the material is metallic and that there is a strong hybridization between N and Ta atoms in the valence band region. The stoichiometric hexagonal e-TaN phase is shown in Figs.3(a) and 3(b). There are six atoms in the unit cell. The calculated equilibrium volume is 0.7% less than the experimental value. From the DOS [Fig. 3(c)] it can be seen that there is also strong hybridization between N and Ta atoms in the valence band region. Finally, the atomic geometry of hexagonal Ta2N is presented in Figs. 3(d) and 3(e). There are just three atoms in the unit cell. The equilibrium volume is calculated to be 0.6% smaller than experiment. The DOS shows clearly that this material is metallic; it can furthermore be seen from the partial DOS that the states above -5 eV are
largely Ta derived.

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1楼 2011-03-08 16:04:44

已阅回复此楼关注TA 给TA发消息送TA红花 TA的回帖

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至尊木虫 (职业作家)

寂寞倾城(金币+20, 翻译EPI+1): 2011-03-09 13:28:24

图2（a）和图2（b)画出了Ta3N5（三钽五氮）相的结构。每个Ta原子被留个N原子包围，而N原子数为与其连接的Ta原子数的3倍和4倍。发现经优化的体积仅比实验结果小0.1% 。晶胞中有32个原子。对应的DOS（态密度）(见图2(c)）(参考文献10）显示此材料是绝缘性的---即，其属于拥有1.5ev禁带宽的半导体。我们注意到，由于对LDA众所周知的低估的因素，实际上此禁带宽将更大一些。通过自能量GW逼近、掩蔽交互（SX）LDA 、自交互修正（SIC）或精确交互计算等方法进行准粒子计算，这样就可得到此禁带宽的更准确的描述。