二氧化镎LDA +U和GGA +U的第一性原理研究
First-principles LDA+U and GGA+U study of neptunium dioxide
摘要：
我们进行了系统的第一性原理研究，计算的电子结构，力学性能，声子色散曲线的NpO $_{2}$。局域密度近似$+U$和广义梯度近似$+U$的形式已被用来解释强烈的本地Np $5f$电子之间的库仑排斥。通过选择Hubbard \emph{U}参数在4 eV左右，Np 5 \emph{f}和O2 \emph{p}的轨道占据特性与最近的实验结果吻合得很好[J. Nucl. Mater. \textbf{389}，470（2009）]。与我们以前对ThO $_{2}$的研究相比，我们注意到Np O $_{2}$中存在更强的共价性，这是由于Np的5个\emph{f}电子的更多局域化行为与锕系元素所表现出的局域化-离域化趋势一致。
英文摘要：
We have performed a systematic first-principles investigation to calculate the electronic structures, mechanical properties, and phonon dispersion curves of NpO$_{2}$. The local density approximation$+U$ and the generalized gradient approximation$+U$ formalisms have been used to account for the strong on-site Coulomb repulsion among the localized Np $5f$ electrons. By choosing the Hubbard \emph{U} parameter around 4 eV, the orbital occupancy characters of Np 5\emph{f} and O 2\emph{p} are in good agreement with recent experiments [J. Nucl. Mater. \textbf{389}, 470 (2009)]. Comparing with our previous study of ThO$_{2}$, we note that stronger covalency exists in NpO$_{2}$ due to the more localization behavior of 5\emph{f} electrons of Np in line with the localization-delocalization trend exhibited by the actinides series.
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