Density functional calculations of Ge(105): Local basis sets and O(N) methods
Density functional calculations of Ge(105): Local basis sets and O(N) methods
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DOI：
10.1103/physrevb.76.115327
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发表时间：
2007-09
影响因子：
3.7
通讯作者：
T. Miyazaki;D. Bowler;R. Choudhury;M. Gillan
中科院分区：
文献类型：
--
作者：
T. Miyazaki;D. Bowler;R. Choudhury;M. Gillan
Ge（105）表面最近引起了人们的关注，一方面是因为对重建本身的兴趣，另一方面是因为Ge在Si（001）上异质外延过程中形成的三维hut团簇的面是应变的Ge（105）表面。我们使用局部基集对该表面进行密度泛函理论（DFT）研究，为Si上全簇簇的O(N) DFT研究做准备（001）。讨论了两个方面。首先，采用离散傅立叶变换和紧密结合的方法对形成表面重构的二聚体进行了详细的屈曲结构建模；发现两种不同的结构在稳定性上接近，其中第二种结构可能对构建小屋簇面很重要[与完美的Ge（105）表面相反]。其次，以0 (N)次计算为目标，研究了局部基集计算DFT的精度。考虑了两种不同的基集：B样条，也称为点，和伪原子轨道；B样条曲线可以非常精确地再现平面波计算的结果。研究了不同计算模式（从非自洽从头算紧绑定到全DFT）的精度，以及O(N)运算的截止半径的影响。这些结果都表明，对该系统进行精确的线性尺度DFT计算是可能的，并给出了不同定位准则引入的误差的定量信息。
The Ge(105) surface has attracted attention recently, both from interest in the reconstruction itself and because the facets of three-dimensional hut clusters which form during heteroepitaxy of Ge on Si(001) are strained Ge(105) surfaces. We present density functional theory (DFT) studies of this surface using local basis sets as a preparation for O(N) DFT studies of full hut clusters on Si(001). Two aspects have been addressed. First, the detailed buckling structure of the dimers forming the surface reconstruction is modeled using DFT and tight binding; two different structures are found to be close in stability, the second of which may be important in building hut-cluster facets [as opposed to perfect Ge(105) surfaces]. Second, the accuracy that can be achieved using local basis sets for DFT calculations is investigated, with O(N) calculations as the target. Two different basis sets are considered: B splines, also known as blips, and pseudoatomic orbitals; B splines are shown to reproduce the result of plane-wave calculations extremely accurately. The accuracy of different modes of calculation (from non-self-consistent ab initio tight binding to full DFT) is investigated, along with the effect of cutoff radius for O(N) operations. These results all show that accurate, linear-scaling DFT calculations are possible for this system and give quantitative information about the errors introduced by different localization criteria.