ELECTRON-POSITRON CAR-PARRINELLO METHODS - SELF-CONSISTENT TREATMENT OF CHARGE-DENSITIES AND IONIC RELAXATIONS
ELECTRON-POSITRON CAR-PARRINELLO METHODS - SELF-CONSISTENT TREATMENT OF CHARGE-DENSITIES AND IONIC RELAXATIONS
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DOI：
10.1103/physrevb.52.10947
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发表时间：
1995-10-15
影响因子：
3.7
通讯作者：
NIEMINEN, RM
中科院分区：
文献类型：
--
作者：
PUSKA, MJ;SEITSONEN, AP;NIEMINEN, RM
提出了一种基于双分量密度泛函理论的具有定域正电子的电子系统的计算方法。电子-离子和正电子-离子相互作用分别用范数守恒的赝势和全离子势来描述，电子和正电子密度分别用电子平面波展开和正电子波函数的实空间网格法自洽地求解。利用第一性原理方法确定了被困在开放体积缺陷处的正电子对离子施加的力和随后的离子弛豫。在半导体的情况下，发现电子和正电子密度的自一致解以及离子位置在构造有效势时强烈依赖于电子-正电子相关的处理。我们考虑了相关能的几种近似，同时通过计算GaAs中被Ga空位捕获的正电子来演示该方法。特别讨论了对可观测到的正电子湮灭特性的影响，即正电子寿命、核心湮灭线形状和二维角相关图。
A calculation method based on the two-component density-functional theory is presented for electron systems with a localized positron. Electron-ion and positron-ion interactions are described by norm-conserving pseudopotentials and full ionic potentials, respectively, The electron and positron densities are solved self-consistently using a plane-wave expansion for electron and a real-space grid method for positron wave functions, respectively. The forces on ions exerted by a positron trapped at an open-volume defect and the ensuing ionic relaxations are determined using first-principles methods. In the case of semiconductors, the self-consistent solution of electron and positron densities as well as the ionic positions are found to depend strongly on the treatment of the electron-positron correlation in constructing the effective potentials. We consider several approximations to the correlation energy while demonstrating the method by calculations for a positron trapped by a Ga vacancy in GaAs. Especially, the effects on the observable positron annihilation characteristics, i.e., positron lifetimes, core annihilation line shapes, and two-dimensional angular correlation maps are discussed.