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arXiv 0901.3385cond-mat.mtrl-sci
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He原子嵌入UO2晶体的从头算DFT +U研究

Ab initio DFT+U study of He atom incorporation into UO2 crystals

Denis Gryaznov, Eugene Heifets, Eugene Kotomin

摘要:

我们提出并讨论了密度泛函理论(DFT)的研究结果的一个完美的UO 2晶体和He原子在八面体间隙的位置。我们已经计算了基本的大块晶体的性质和他纳入到低温反铁磁UO 2相使用几个交换相关泛函内的自旋极化局域密度(LDA)和广义梯度(GGA)近似的能量。在所有这些DFT计算中,我们包括使用哈伯德模型(DFT+U方法)的现场相关校正。我们分析了一个潜在的晶体对称性减少,并证实了在一个完美的UO 2的Jahn-Teller效应的存在。我们还讨论了问题的导电电子状态时,他被放置到一个tetrapherases反铁磁相的UO 2。因此,我们发现了一个特定的晶格畸变,使我们能够恢复半导体状态,并正确估计他的掺入能量。与体性质不同,He掺入能量强烈依赖于几个因素,包括超晶胞尺寸、自旋极化的使用、交换相关泛函和现场相关校正。我们比较我们的结果与以前的壳模型和从头算DFT计算的他掺入。

英文摘要:

We present and discuss results of a density functional theory (DFT) study of a perfect UO2 crystals and He atoms in octahedral interstitial positions. We have calculated basic bulk crystal properties and He incorporation energies into the low temperature anti-ferromagnetic UO2 phase using several exchange-correlation functionals within the spin-polarized local density (LDA) and generalized gradient (GGA) approximations. In all these DFT calculations we included the on-site correlation corrections using the Hubbard model (DFT+U approach). We analysed a potential crystalline symmetry reduction and confirmed the presence of the Jahn-Teller effect in a perfect UO2. We discuss also the problem of a conducting electronic state arising when He is placed into a tetragonal antiferromagnetic phase of UO2. Consequently, we found a specific lattice distortion which allows us to restore the semiconducting state and properly estimate He incorporation energies. Unlike the bulk properties, the He incorporation energy strongly depends on several factors, including the supercell size, the use of spin polarization, the exchange-correlation functionals and on-site correlation corrections. We compare our results for the He incorporation with the previous shell model and ab initio DFT calculations.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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