我們利用虛函數(pseudofunction)(PSF)方法及局部電子自旋密度近似法(local-spin-density approximation) (LSDA)計算鈦酸鋇鍶(Ba1-xSrxTiO3)(BSTO), x = 0, 0.25, 0.5, 0.75, 1結晶的電子結構及總電子能態密度(TDOS)及部分電子能態密度(PDOS). 我們發現計算出的直接能隙Eg隨著Sr參雜量的函數曲線向上凸起，此結果可歸因於由實驗晶格常數所得的Ti-O鍵長的Sr的參雜量函數曲線向下凹陷。計算所得BaTiO3及SrTiO3 O-p的部分電子能態密度(PDOS)的主要高峰位置與O K-edge XANES光譜的結果,同時兩材料所計算出的總電子能態密度(TDOS)及價電帶寬度皆符合UPS光譜的結果.

We use the spin polarized pseudofunction(PSF) method with the local-spin-density approximation (LSDA) to calculate the electronic structures and the total and partial charge densities (TDOS, PDOS) of bulk Ba1-xSrxTiO3 (BSTO) with x = 0, 0.25, 0.5, 0.75, and 1. We find that the calculated direct energy gap Eg bows up as a function of the Sr concentration, which is related to the bowling downward of the Ti-O bond length inferred from the experimental lattice constants. The calculated partial densities of unoccupied O-p derived states (PDOS) agree well with the features observed in the O K-edge XANES spectra of BaTiO3 and SrTiO3. The calculated total densities of valence-band states (TDOS) and the valence-band widths for BaTiO3 and SrTiO3 agree well with the UPS spectra.

Ⅰ Introduction 1
Ⅱ Theory
2-1 Introduction
2-2 Density Functional Theory (DFT) with Local-Spin- Density Approximation
(LSDA)
2-3 The Pseudofunction (PSF) Method
Ⅲ Calculation Details
Ⅳ Results and Discussion
Ⅴ Summary
References
Tables
Figure Captions

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