中文摘要：

基于密度泛函理论系统地研究了铀锆合金（γ-UZr和δ-UZr2）的晶体结构、电子结构及化学键性质。鉴于U-5f电子的强关联性,使用局域密度近似（LDA）和LDA＋U（U=4eV）方法对比研究了铀锆合金的基态性质。尽管这两种方法计算所得的晶格常数均略小于实验值,但总体上与实验还是符合的很好。与纯LDA相比,加U=4eV的计算结果显示5f电子的库仑排斥作用对合金体系电子态密度分布的影响极小。因此可忽略U-5f的库仑排斥作用。两种构型合金体系的总态密度分布表明它们在费米能级附近的电子占据主要是U-5f和Zr-4d,并有明显的杂化。在γ-UZr和δ-UZr2中,U—Zr键间均显示微弱的共价性,其中U—Zr2共价性最强（0.048e/au3）,U—Zr次之（0.040e/au3）,U—Zr1最弱（0.032e/au3）,而δ-UZr2中的Zr1离子性最强。

英文摘要：

We investigated the lattice structure,electronic structure,and chemical bonding properties of the uranium-zirconium alloys（γ-UZr andδ-UZr2）based on the first-principles calculations.In view of the localization behavior of U-5felectrons,the local density approximation（LDA）＋U approach was employed to simulate the groud-state properties of U-Zr alloys in comparison with the pure LDA.Our conclusion is consistent with the experiment,although the lattice parameters produced by the two methods are both slightly less than experimental data.Comparing with LDA method,the strong coulomb repulsion of 5felectrons affects the electronic density of states negligibly.Therefore,we neglected the coulomb repulsion of U-5f.The total density of states distributions of UZr alloys indicated that U-5fand Zr-4doccupied the Fermi level primarily and hybridized.Besides,a weak covalent component exists between U ions and their nearest neighboring Zr ions forγ-UZr andδ-UZr2,in which U—Zr bond（0.040e/au3）is prominently weaker than the U—Zr2bond（0.048e/au3）while stronger than U—Zr1bond（0.032e/au3）.Meanwhile,more electrons are released from Zr1 to bond with U inδ-UZr2.