Newly Implemented Parallel TDDVR Method for Quantum-Classical Investigation of the Pentafluorobenzene Radical Cation (C 6 HF 5 + )

We present a newly implemented, parallelized version of the quantum-classical time-dependent discrete variable representation (TDDVR) method and apply it to investigate the nonadiabatic dynamics of the pentafluorobenzene radical cation (PFBz+/C6HF5+). The PFBz+ shows a complex manifold of conical intersections (CIs) among its six lowest electronic states (X2A2, A2B1, B2B1, C2B2, D2A1, and E2B2), which are strongly coupled via Jahn-Teller and pseudo-Jahn-Teller interactions within a 30-mode diabatic model Hamiltonian. The parallel algorithm demonstrates near-linear scalability with the number of processors, enabling the efficient quantum-classical simulation of this high-dimensional system. The key dynamical observables are computed as state-resolved populations, photoelectron (PE) spectra, resonance-enhanced multiphoton ionization (REMPI) spectra of the neutral molecule, and a theoretical mass-analyzed threshold ionization (MATI) spectrum for PFBz+. The simulated PE and REMPI spectra show very good agreement with experimental benchmarks. The predicted MATI spectrum illustrates the extensive spectral broadening caused by strong vibronic coupling (VC). This work validates the parallel TDDVR method as an efficient and reliable tool for simulating complex nonadiabatic dynamics and spectroscopy in polyatomic systems, effectively bridging high-level theoretical simulations with ultrafast experimental spectroscopy.