Phase stability and structural distortion of NiO under high pressure
(1.Key Laboratory of Advanced Materials and Ryeological Properties of Ministry of Education,Department of Physics, Xiangtan University 411105, China2.广西壮族自治区南宁市广西大学化学化工学院3.湖南省湘潭市湘潭大学材料与光电物理学院)
Abstract: The phase stability and structural distortion of NiO under high pressure were investigated using first-principles calculations based on density-functional theory. Different forms of exchange-correlation functional including LDA, GGA and GGA+U were used in the present calculations. All of the three methods predict NiO to be AFM II ordering with the cell slightly compressed along [111] direction and also indicate that there is no structural phase transition of NiO under pressure up to 140 GPa, which are in agreement with the experiment. However, both LDA and GGA incorrectly predict the structural distortion under pressure especially above 60 GPa. Only when strong correlations are included in form of GGA+U, structural distortion under high pressure can qualitatively agree with the experiment. The related mechanism was also analyzed and discussed. These results suggest that the strong electronic correlations still play a very important role in the properties of NiO under high pressure.
Key words: NiO; phase stability; structural distortion; strong correlation; first-principles calculation; high pressure