Authors: Sangita Majumdar, Zekun Shi, Giovanni Vignale
Conference: Psi-k 2025
We present (1) a constrained search method for the noninteracting kinetic energy functional T_s[n] for periodic densities, which has analytical functional derivative V_s[n] at fixed electron number; (2) a routine for the derivative discontinuity—the uniform shift in V_s[n] upon changing particle number—thereby diagnosing noninteracting insulators vs conductors. The method uses the equidensity orbital (EO) basis and QR-based Stiefel manifold retraction. Benchmarks on 1D periodic systems reach chemical accuracy, indicating a viable path toward orbital-free treatments of periodic materials and novel way to invert periodic densities to obtain the Pauli potential for practical systems.