The role of the coupling matrix elements in time-dependent density functional theory on the simulation of core-level spectra of transition metal complexes
Abstract
Time-dependent density functional theory (TD-DFT) stands out as an efficient tool for computing core-level spectra in large molecules, particularly transition metal complexes. However, despite their relatively moderate computational demands, TD-DFT methods can still pose challenges for typical computations involving transition metal complexes with over a thousand basis functions. In this study, we investigate the role of the Coulomb, Hartree-Fock exchange, and exchange-correlation kernel contributions to the TD-DFT coupling matrix elements when simulating core-level spectra in transition metal complexes. Our observations reveal that the exchange-correlation kernel contribution, responsible for more than 50% of the computational time in a hybrid TD-DFT calculation, surprisingly has no discernible impact on the qualitative aspects of the calculated spectra. While the Coulomb term plays a crucial role in describing L 2 , 3 -edge spectra, its significance becomes negligible when considering K, L 1, and M 4 , 5 edges. In contrast, the scaled Hartree-Fock exchange is demonstrated to be the most influential term, underscoring the necessity for hybrid density functional approximations in accurately simulating core-level spectra. These trends hold irrespective of the chosen basis set and exchange-correlation functional, providing valuable insights for the development of approximate methods for incorporating two-electron interactions within the realm of core-level spectroscopies.
Publication Title
Electronic Structure
Recommended Citation
Pak, S., & Nascimento, D. (2024). The role of the coupling matrix elements in time-dependent density functional theory on the simulation of core-level spectra of transition metal complexes. Electronic Structure, 6 (1) https://doi.org/10.1088/2516-1075/ad2693
