Modular integration of MRSF-TDDFT, NAMD, and QM/MM for excited-state dynamics on the OpenQP platform.

A balanced and efficient description of excited states is essential for accurately capturing ultrafast relaxation processes. In this context, the recently developed mixed-reference spin-flip time-dependent density functional theory (MRSF-TDDFT) has demonstrated strong performance. However, its broader applicability to realistic systems requires seamless integration with multiscale simulation frameworks. In this work, we present a modular strategy that integrates MRSF-TDDFT with nonadiabatic molecular dynamics (NAMD) and electrostatic potential fitting (ESPF)-based QM/MM embedding methodologies, in which OpenQP (Open Quantum Platform) serves as a modular electronic-structure backend. To further enhance usability and interoperability, we introduce the Open Simulation Manager (OpenSM), a high-level orchestration framework that unifies QM, QM/MM, and NAMD workflows through a consistent and minimal input interface. The resulting OpenQP-OpenSM provides a flexible and extensible platform for multiscale excited-state simulations, enabling rapid integration of advanced electronic-structure methods and fostering collaborative development.