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钚氧化层结构的理论研究进展
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作者 谢刘桦 邱睿智 《核化学与放射化学》 CAS CSCD 北大核心 2023年第5期389-396,共8页
钚的氧化层结构是钚化学腐蚀的中心科学问题,本文回顾了本课题组最近在这方面的理论研究工作。首先,基于第一性原理计算结合化学热力学,说明单氧化钚在常压下是热力学不稳定的,可能分解成Pu_(2)O_(3)和钚,但是压强可以将单氧化钚稳定下... 钚的氧化层结构是钚化学腐蚀的中心科学问题,本文回顾了本课题组最近在这方面的理论研究工作。首先,基于第一性原理计算结合化学热力学,说明单氧化钚在常压下是热力学不稳定的,可能分解成Pu_(2)O_(3)和钚,但是压强可以将单氧化钚稳定下来,电子结构计算说明了其中的稳定机制。其次,基于准随机结构的第一性原理计算,说明碳也可以将单氧化钚稳定下来。并且重现了碳氧化钚的晶格常数反常演化并阐释其微观电子结构机制。最后,基于类比镧系的过渡氧化物结构模型,预测在Pu_(2)O_(3)/PuO_(2)层中存在低对称结构的Pu_(n)O_(2 n-2)。基于这些工作,提出了一种阶梯状的氧化层结构模型(Pu/PuO_(x)C_(y)/Pu_(2)O_(3)/Pu_(n)O_(2 n-2)/PuO_(2)),以改进简单的三明治状氧化层模型。这个结构模型为钚的化学腐蚀研究提供了一定的理论指导价值。 展开更多
关键词 钚氧化层结构 单氧化钚 碳氧化钚 过渡氧化物 电子结构 第一性原理计算
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Site selective 5f electronic correlations inβ-uranium
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作者 邱睿智 谢刘桦 黄理 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第1期421-426,共6页
We investigate the electronic structure ofβ-uranium,which has five nonequivalent atomic sites in its unit cell,by means of the density functional theory plus Hubbard-U correction with U from linear response calculati... We investigate the electronic structure ofβ-uranium,which has five nonequivalent atomic sites in its unit cell,by means of the density functional theory plus Hubbard-U correction with U from linear response calculation.It is found that the 5f electronic correlations inβ-uranium are moderate.More interestingly,their strengths are site selective,depending on the local atomic environment of the present uranium atom.As a consequence,the occupation matrices and partial 5f density of states ofβ-uranium manifest site dependence.In addition,the complicate experimental structure ofβ-uranium could be well reproduced within this theoretical framework. 展开更多
关键词 URANIUM low-symmetry crystal structure 5f electronic correlation SITE-SELECTIVITY density-functional theory
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Effect of strain on charge density wave order inα-U
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作者 谢刘桦 袁宏宽 邱睿智 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第6期643-649,共7页
The effect of strain on charge density wave(CDW)order inα-U is investigated within the framework of relativistic density-functional theory.The energetical stability ofα-U with CDW distortion is enhanced by the tensi... The effect of strain on charge density wave(CDW)order inα-U is investigated within the framework of relativistic density-functional theory.The energetical stability ofα-U with CDW distortion is enhanced by the tensile strain along a and b axes,which is similar to the case of negative pressure and normal.However,the tensile strain along c axis suppresses the energetical stability of CDW phase.This abnormal effect could be understood from the emergence of a new onedimensional atomic chain along c axis inα-U.Furthermore,this effect is supported by the calculations of Fermi surface and phonon mode,in which the topological objects and the dynamical instability show opposite behaviors between strains along a/b and c axes. 展开更多
关键词 URANIUM charge density wave strain effect density-functional theory
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