Spin-dependent excited-state calculations in plane wave linear-response time-dependent density functional theory: Implementation and benchmarking

Spin-dependent linear-response time-dependent density functional theory has emerged as a powerful computational tool for accurately describing electronic excitations in complex spin-dependent systems. In this work, we introduce an efficient numerical implementation integrated into our open-source software KSSOLV (Kohn–Sham Solver) with plane wave basis sets, which systematically treats both spin-conserving and spin–flip excitation processes. Through comprehensive benchmark calculations, we validate both the numerical accuracy and computational efficiency of our implementation using representative molecular and periodic systems. In particular, the benchmarks encompass closed-shell molecules, such as nitrogen (N2), water (H2O), and carbon monoxide (CO), and the open-shell molecule oxygen (O2), along with periodic examples, including spin-unpolarized silicon (Si64) and the negatively charged nitrogen-vacancy center (NV−) in diamond. Comparative analyses with established quantum chemistry and materials science codes utilizing the Gaussian-type orbitals and plane wave basis sets confirm its robustness and capability to address previously challenging spin-dependent periodic systems.