First-principles molecular orbital calculation of electron energy-loss near-edge structures of -quartz
First-principles molecular orbital calculation of electron energy-loss near-edge structures of -quartz
复制标题
石英近边结构电子能量损失的第一性原理分子轨道计算
DOI：
10.1088/0022-3727/29/7/007
复制
发表时间：
1996
期刊：
影响因子：
--
通讯作者：
H. Adachi
中科院分区：
文献类型：
--
作者：
I. Tanaka;H. Adachi
我们报告了用离散变分方法对石英模型簇进行第一性原理分子轨道计算的结果。为了评估与电子能量损失过程相关的核心空穴的存在所产生的影响，对包含半填充的核心空穴（即在斯莱特过渡态）的团簇进行了自一致计算。半填充的Si-2p岩心孔的存在并没有显著改变Si-3s/3d态偏密度（PDOS）。另一方面，当引入半填充的O-1s孔时，O-2p PDOS出现了显著的岩心孔效应。计算得到的过渡态PDOS与边缘和O-K边缘的电子能量损失近边结构（ELNES）吻合较好。当考虑跃迁过程中的自旋极化时，两边的绝对跃迁能量也被复制到误差在3ev以内。根据第一性原理计算了光吸收截面（PACS），并与相应电偶极子跃迁的PDOS进行了比较。在本计算中，PACS和PDOS在基态和斯莱特跃迁态的差异都很小。
We report results of first-principles molecular orbital calculations using the discrete-variational method on a model cluster of -quartz . Self-consistent calculations of the cluster which include a half-filled core hole, i.e. at Slater's transition state, are made in order to evaluate the effect arising from the presence of a core hole associated with the electron energy-loss process. The presence of a half-filled Si-2p core hole does not change the unoccupied Si-3s/3d partial density of states (PDOS) significantly. On the other hand, a remarkable core hole effect appears on O-2p PDOS when a half-filled O-1s hole is introduced. The calculated PDOS at the transition states is in good agreement with the electron energy-loss near-edge structures (ELNES) at both the edge and O-K edge. Absolute transition energies at both edges are also reproduced to within an error of 3 eV when spin-polarization during the transition is taken into account. The photoabsorption cross sections (PACS) are calculated from first principles and are compared with the PDOS for the corresponding electric dipole transitions. The difference between the PACS and the PDOS is found to be small at both the ground state and the Slater's transition state in the present calculation.