研究CuB2O4反鐵磁性材料在第一原理中的能帶架構以及材料特性。
CuB2O4在第一原理中，使用六個單元的方式呈現週期性的結構分布，在這個晶格中a=11.357、c=5.542 Å, k-mesh使用4x4x4, nbands為400 並且使用VASP GGA+U的方法，其中Cu(A)&Cu(B)的U分別為U1=6.4eV, U2=7.0eV。
在計算中，我們發現CuB2O4的density of state(DOS)在導帶的地方會出現兩個非常明顯的尖點。一個是由Cu(A)&O(1)組成，另外一個則是由Cu(B)&O(2)&O(3)&O(4)所貢獻，因此我們希望可以分析出兩者的不同。

Ab initio study of anti-ferromagnetic non-collinear CuB2O4 crystal ,CuB2O4 crystallizes in first-principles calculations, with six formula units were performed using periodic density function theory. The cell of dimensions a=11.357 and c=5.542 Å, k-mesh=4x4x4, nbands=400 and use GGA+U on VASP where U1=6.4eV, U2=7.0eV for Cu(A)&Cu(B).In the case, we found that CuB2O4’s density of state(DOS) has two peaks in conduction band. One is contributed by Cu(A) & O(1), the other one is contributed by Cu(B) & O(2) & O(3) & O(4). As the result of, we can sort atoms to two types. A type is Cu(A) and O(1) which donate states to peak(1), the other type is Cu(B) and O(2)&O(3)&O(4) which donate states to peak(2). And we could do analyze their difference.

Chapter1 緒論 1

Chapte2 密度泛函理論(DFT)和計算方法 2
2.1 密度泛函理論(Density function theory) 2
2.1.1 The Hohenberg-Kohn theorems 2
2.1.2 The Kohn-Sham equations 4
2.1.3 Exchange-correlation energy 6
2.2 GGA+U method 7

Chapter3 CuB2O4的文獻探討 8
3.1 CuB2O4在基態時的鐵磁性研究(Ferromagnetism in CuB2O4) 8
3.2 CuB2O4在VASP中的鐵磁性計算研究 11

Chapter4 CuB2O4在VASP中的材料計算研究及討論 15
4.1 CuB2O4在VASP中的自洽(self-consistent field method, SCF)材料計算 15
4.2 CuB2O4在VASP中使用GGA+U方法的計算 16
4.2.1 在VASP測試U值的大小 16
4.2.2 CuB2O4在VASP中的收斂(relaxation)計算 19
4.3 CuB2O4材料在導帶上的特徵分析 24

Chapter5 結果與討論 29

參考文獻 31

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