Mitra Chandrima, Krogel Jaron T, Santana Juan A, Reboredo Fernando A
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
J Chem Phys. 2015 Oct 28;143(16):164710. doi: 10.1063/1.4934262.
We present a many-body diffusion quantum Monte Carlo (DMC) study of the bulk and defect properties of NiO. We find excellent agreement with experimental values, within 0.3%, 0.6%, and 3.5% for the lattice constant, cohesive energy, and bulk modulus, respectively. The quasiparticle bandgap was also computed, and the DMC result of 4.72 (0.17) eV compares well with the experimental value of 4.3 eV. Furthermore, DMC calculations of excited states at the L, Z, and the gamma point of the Brillouin zone reveal a flat upper valence band for NiO, in good agreement with Angle Resolved Photoemission Spectroscopy results. To study defect properties, we evaluated the formation energies of the neutral and charged vacancies of oxygen and nickel in NiO. A formation energy of 7.2 (0.15) eV was found for the oxygen vacancy under oxygen rich conditions. For the Ni vacancy, we obtained a formation energy of 3.2 (0.15) eV under Ni rich conditions. These results confirm that NiO occurs as a p-type material with the dominant intrinsic vacancy defect being Ni vacancy.
我们展示了一项关于NiO体相和缺陷性质的多体扩散量子蒙特卡罗（DMC）研究。我们发现，对于晶格常数、内聚能和体模量，与实验值分别在0.3%、0.6%和3.5%的范围内具有极佳的一致性。还计算了准粒子带隙，DMC结果为4.72（0.17）eV，与4.3 eV的实验值相当吻合。此外，在布里渊区的L、Z和Γ点对激发态进行的DMC计算表明，NiO具有一个平坦的上价带，这与角分辨光电子能谱结果高度一致。为了研究缺陷性质，我们评估了NiO中氧和镍的中性及带电空位的形成能。在富氧条件下，氧空位的形成能为7.2（0.15）eV。对于镍空位，在富镍条件下我们得到的形成能为3.2（0.15）eV。这些结果证实，NiO是一种p型材料，主要的本征空位缺陷是镍空位。
