應用計算：我們將LDA+U方法用在過渡金屬氧化物晶體KNbO3 ,發現對倍頻係數的正確性有提升,我們對此情形做仔細的探討.另外我們對各種不同的新奇結構所引發的非線性光學效應很感興趣,所以論文中我選定了BN錐狀結構(cone)且建構了不同角度的結構來計算並且使用能帶解析以SHG-density分析方法來分析. Methodology : The DFT bases code CASTEP was used in our group for many successful studies of materials properties of various system. However for transition metal Oxides there localized d-electron cause the calculate SHG coefficient to be not accurate . We used LDA+U to correct the problem which was demonstrated using old CASTEP code. Now we would like to implement LDA+U into New CASTEP.
Applications : We are using the LDA+U method on KNbO3 crystal of transition metal Oxides ,and we find the exactness of SHG coefficient improves , We do the detailed discussion. Another , we are interested in non-liner optical effect of many different novel structure , so I choose BN cone and building structures with different disclination angle to caculate and analyse with band-resolved of and SHG-density plots.