SC Colloquium: "Patching Exchange-Correlation Potential in Density Functional Theory"
Department of Scientific Computing
Florida State University
Abstract:
To compute the electronic structures of large correlated materials, we need to scale up high-level quantum mechanics calculations. Kohn-Sham density functional theory (DFT) is an exact theory with the exact exchange-correlation (XC) potential. Based on this fact, we developed a simple method to directly construct XC potentials in large systems. The method consists of two steps: (a) the density partitioning and (b) the XC potential patching. To partition the system, we divide the total system’s Kohn-Sham potential among a cluster and its environment. An embedding potential, which “glues” the cluster and its environment together, is then constructed such that the sum of the cluster and environment densities matches the total system’s electron density. Due to the one-to-one mapping between density and XC potential, the cluster’s XC potential can be computed by inverting its density using certain high-level methods (such as advanced orbital-based XC functionals). For the step of patching, we derived two XC potential patching methods. For the local XC potential patching, the total system’s XC potential is updated in the cluster’s region. We demonstrated that the coupling between a cluster and its environment is important for achieving a fast convergence of the electronic structure in the cluster region. For the global XC patching, we project the cluster’s XC potential to its central atom. We then patch the XC potentials of all the central atoms over the entire system.