Determining Hubbard U of VO2 by the quasi-harmonic approximation

Vanadium dioxide VO 2 is a strongly correlated material that undergoes a metal-to-insulator transition around 340 K. In order to describe the electron correlation effects in VO 2 , the DFT + U method is commonly employed in calculations. However, the choice of the Hubbard U parameter has been a subject of debate and its value has been reported over a wide range. In this paper, taking focus on the phase transition behavior of VO 2 , the Hubbard U parameter for vanadium oxide is determined by using the quasi-harmonic approximation (QHA). First-principles calculations demonstrate that the phase transition temperature can be modulated by varying the U values. The phase transition temperature can be well reproduced by the calculations using the Perdew–Burke–Ernzerhof functional combined with the U parameter of 1.5 eV. Additionally, the calculated band structure, insulating or metallic properties, and phonon dispersion with this U value are in line with experimental observations. By employing the QHA to determine the Hubbard U parameter, this study provides valuable insights into the phase transition behavior of VO 2 . The findings highlight the importance of electron correlation effects in accurately describing the properties of this material. The agreement between the calculated results and experimental observations further validates the chosen U value and supports the use of the DFT + U method in studying VO 2 .