分子磁體nafe39;ⅱ,2(po,4)(hpo,4)的磁性及電導(dǎo)性的第一性原理研究

1、煙臺大學(xué)碩士學(xué)位論文分子磁體NaFe（PO）（HPO）的磁性及電導(dǎo)性的第一性原理研究姓名：王燕申請學(xué)位級別：碩士專業(yè)：理論物理指導(dǎo)教師：孫玉明20080331IIAbstract In this thesis, first-principle calculations have been performed to study the electronic structure and the magnetic properties of

2、non-pure organic magnet NaFeⅡ 2(PO4)(HPO4). All calculations were performed using a full potential linearized augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). To test the accuracy and p

3、recision of FP-LAPW method, the electronic structure and ferroelectric properties of the simple bulk BaTiO3 were first studied. The analysis of the partial density of states indicates that Ti 3d states and O 2p states ar

4、e greatly overlapped, showing strong hybridization between them. This orbital hybridization may lead to the spontaneous polarization in octahedron, and it results in aligned electric dipoles in bulk BaTiO3, presenting fe

5、rroelectric property. External pressure and temperature can induce ferroelectric phase transition of BaTiO3 because of changed orbital hybridization. For metal phosphonates NaFeⅡ 2(PO4)(HPO4), a stable antiferromagnetic

6、(AFM) ground state and a ferromagnetic (FM) metastable state were found in agreement with the experimental results. The calculated spin magnetic moment per molecule is 7.00µB, mainly from the FeⅡ. Density of states

7、shows that NaFeⅡ 2(PO4)(HPO4) is characteristic of semiconductor and conductor in AFM and FM states respectively. In order to further investigate the conductivity properties in FM and AFM states, we also give the electro

8、nic band structure, it is found that the bands have significant overlaps between the highest occupied molecule orbital (HOMO) and lowest unoccupied molecule orbital (LUMO) of spin-up and spin-down in FM states, while an

9、energy gap of about 0.2eV in AFM states, based on this we can conclude that the FM metastable state has conductor properties, but AFM ground state has semiconductor properties. Keywords: density functional theory, FP-LAP