CuB2O4晶體在第一原理的研究

Ab initio study of the anti-ferromagnetic, non-collinear CuB2O4 crystal

王俊凱(Wang Chun-Kai)

指導教授 ： 陳穎叡

國立臺灣師範大學/理學院/物理學系/碩士(2019年)

https://doi.org/10.6345/THE.NTNU.DP.001.2019.B04

摘要

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。

關鍵字

第一原理 ； 晶體結構 ； 能帶分析

並列摘要

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.

並列關鍵字

Ab initio ； VASP ； first-pronciple ； CuB2O4 ； non-collinear calculation

參考文獻

1.Andreas Go¨rling. Density-functional theory beyond the Hohenberg-Kohn theorem. Phys. Rev. A 59,3359 (1999)

2.A.I.Liechtenstein, V.I.Anisimov, and J.Zaanen. Density-functional theory and strong interactions: Orbital ordering in Mott-Hubbard insulators. Phys. Rev. B 52, R5467(R)(1995)

3.C.F. von WEIZSÄCKER. Z. Phys. 96, 431 (1935)

4.John P. Perdew and Mel Levy. Physical Content of the Exact Kohn-Sham Orbital Energies: Band Gaps and Derivative Discontinuities. Phys. Rev. Lett. 51, 1884(1983)

5.Larry Spruch. Pedagogic notes on Thomas-Fermi theory (and on some improvements): atoms, stars, and the stability of bulk matter. Rev. Mod. Phys. 63, 151 (1991)