At ambient conditions, NiO is a prototypical antiferromagnetic correlated insulator. According to conventional Mott physics, applied pressure is expected to reduce the band gap and induce an insulator-to-metal transition. However, first-principles simulations consistently predict metallization pressures around 1 TPa, far exceeding the experimentally observed value of approximately 240 GPa. This significant discrepancy highlights a limitation in the prevailing theoretical understanding. Here, we employ the method that incorporates pressure-dependent electronic correlations parameters to reinvestigate this longstanding issue by systematically evaluating the roles of electronic structure, magnetic order, and crystal structure. Our simulations suggest that the pressure-dependent electronic correlations, coupled with a potential structural transition constitute the primary driving force of the insulator-metal transition at experimentally observed pressures. Incorporating pressure-dependent electronic correlations allows accurate determination of the band gap of insulating state and the prediction of a $B1\text{−}B2$ structural transition near the experimentally reported pressure. Moreover, this structural transition triggers a crystal-field inversion that partially fills the $t_{2\mathrm{g}}$ orbitals, leading to metallic behavior.

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• High-pressure studies
• Metal-insulator transition
• Strongly correlated systems
• Density functional calculations