Localized Basis Set Density Functional Theory Study:The calculation of Spin Density and Atomic Charge of LaMnO3

• Main Authors: Wei-Lin Pan, 潘煒琳
• Other Authors: Cheng-Hsuan Chen
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/58486307550956553687

碩士 === 國立臺灣大學 === 物理研究所 === 94 === The spin and charge densities of ABO3(A=La，B=Mn) with a cubic unit cell has been studied using periodic boundary condition and localized basis sets. The calculation method performed through this work is density functional theory (DFT) with the functional BLYP. We have discussed the changes of spin density and atomic charge on B-site (Mn) as the crystal parameters are individually expanded or compressed from 0.02% to 0.2%(and, from 0.5%~5.5%). In the calculations of both single-unit-cell and double-unit-cells (combined by two neighboring single unit cell) cases, there exhibits the highly dependence between the electron spin density and crystal parameter while the changes of electron spin density and atomic charge become smaller as the dimension of expansion (compression) decreases. The spin density of Mn in double-unit-cell case exhibits almost complete inversion (from +4 to -4) at each 0.02% expansion or compression of crystal parameter and it takes nearly twice times of percentage in the same dimension to reach the spin-inversed result in the single-unit-cell one. Finally, the calculation results also show that the atomic charge is almost independent of the change of the crystal parameter.