School of Physics and Electronic Sciences, Changsha University of Science and Technology, Changsha 410004, People's Republic of China.
J Chem Phys. 2013 Jun 28;138(24):244703. doi: 10.1063/1.4811281.
The structural, electronic, magnetic, and elastic properties of hexagonal nickel sulfide (NiS) have been investigated comparatively by Density Functional theory (DFT) and DFT plus correction for on-site Coulomb interaction (DFT+U), in which two different exchange correlation functionals local density approximations (LDA) and general gradient approximations (GGA) in the form of Perdew-Burke-Ernzerhof (PBE) are used. Our results indicate LDA and PBE methods predict hexagonal NiS to be a paramagnetic metal whereas LDA(PBE)+U calculations with reasonable on-site Coulomb interaction energy give the antiferromagnetic insulating state of low temperature hexagonal NiS successfully. Meanwhile, compared with LDA(PBE) results, LDA(PBE)+U methods give larger lattice parameters, crystal volume, and shear constant c44, consistent with the experimental picture during high-low temperature phase transition of hexagonal NiS, in which an increase of the shear constant c44 and lattice parameters were found in the low-temperature antiferromagnetic phase. The present DFT and DFT+U calculations provide a reasonable description for the properties of high temperature and low temperature hexagonal NiS respectively, which indicates that electronic correlation is responsible for this high-low temperature phase transition.
我们使用密度泛函理论（DFT）和加上局域密度近似（LDA）和广义梯度近似（GGA）形式的 Perdew-Burke-Ernzerhof（PBE）两种不同的交换相关泛函，比较研究了六方硫化镍（NiS）的结构、电子、磁和弹性性质。我们的结果表明，LDA 和 PBE 方法预测六方 NiS 是顺磁金属，而具有合理局域库仑相互作用能的 LDA（PBE）+U 计算成功地给出了低温六方 NiS 的反铁磁绝缘态。同时，与 LDA（PBE）结果相比，LDA（PBE）+U 方法给出了较大的晶格参数、晶体体积和剪切常数 c44，这与六方 NiS 高低温相变期间的实验情况一致，在低温反铁磁相中发现了剪切常数 c44 和晶格参数的增加。本研究中的 DFT 和 DFT+U 计算分别为高温和低温六方 NiS 的性质提供了合理的描述，这表明电子相关是导致这种高低温相变的原因。
