Programme

P.23 -- Posters, VCTP-51

Date: Tuesday, 4 August 2026

Time: 09:30 - 10:30

Unveiling Vacancy-Induced Magnetism in TiO2 via Electronic Structure Calculations

Phong Nguyen-Duc (1), Trang Nguyen-Thuy (1), and The Long Phan (2)

(1) Center for Materials Science, Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi, Vietnam. (2) Faculty of Engineering Physics and Nanotechnology, VNU University of Engineering and Technology, Vietnam National University - Hanoi, No. 144 Xuan Thuy Road, Cau Giay Ward, Hanoi, Viet Nam.

We present a theoretical study on vacancy induced magnetism of anatase and rutile Titanium dioxide ($\mathrm{TiO}_2$) based on Density Functional Theory (DFT) calculations. Perdew-Burke-Ernzerhof (PBE) and regularized-restored Strongly Constrained and Appropriately Normed ($r^2\mathrm{SCAN}$) functionals with Hubbard Correction ($\mathrm{DFT}+U$) were employed. While both the PBE and $\mathrm{PBE}+U$ functionals fail to predict the higher stability of the rutile phase over anatase, the $r^2\mathrm{SCAN}+U$ method correctly captures this relative stability. Regarding Ti-vacancy induced magnetism, $\mathrm{PBE}+U$ and $r^2\mathrm{SCAN}+U$ yield closely matching net magnetic moments for anatase, at $3.99\,\mu_{\mathrm{B}}$ and $3.97\,\mu_{\mathrm{B}}$, respectively. However, for the rutile phase, the Ti-vacancy-induced magnetic moment predicted by $\mathrm{PBE}+U$ method, $0.73\,\mu_{\mathrm{B}}$ is less than half of the value obtained with $r^2\mathrm{SCAN}+U$ method, $1.60\,\mu_{\mathrm{B}}$. For O-vacancy induced magnetism, while $r^2\mathrm{SCAN}+U$ method predicts zero net magnetic moment for both phases, $\mathrm{PBE}+U$ yields a non-magnetic state for anatase but a moment of $2.00\,\mu_{\mathrm{B}}$ for rutile. The origins of magnetism and the discrepancies between the functional approximations are thoroughly elucidated through a detailed electronic structure analysis.

Presenter: Nguyen Duc Phong