Pressure Evolution of the Hubbard U in Rare-Earth Metals via the Linear Response Approach

Calculating the properties of rare-earth metals using ab-initio methods is an important component in understanding these strongly correlated materials. Traditional density functional theory (DFT) calculations are insufficient in describing their properties and phase transitions due to electronic correlation effect. On the other hand, the DFT+U approach is a more robust method for obtaining experimentally-consistent electronic and magnetic structures. One critical question, however, is how to determine the Hubbard value from first principles. Here, we employ the linear response approach to calculate the effective U for various rare-earth metals. We study how the U value evolves as a function of unit cell size and structure type. The pressure evolution of the Hubbard U is calculated using both experimental unit cell and DFT relaxed crystal structures. The resulting U values provide important input information for DFT+U calculations to understand the behavior of rare-earth materials and their applications in extreme pressure environments.