Simulating Real-Time\nMolecular Electron Dynamics Efficiently\nUsing the Time-Dependent Density Matrix Renormalization Group

Compared to ground-state electronic structure optimizations,\naccurate\nsimulations of molecular real-time electron dynamics are usually much\nmore difficult to perform. To simulate electron dynamics, the time-dependent\ndensity matrix renormalization group (TDDMRG) has been shown to offer\nan attractive compromise between accuracy and cost. However, many\nsimulation parameters significantly affect the quality and efficiency\nof a TDDMRG simulation. So far, it is unclear whether common wisdom\nfrom ground-state DMRG carries over to the TDDMRG, and a guideline\non how to choose these parameters is missing. Here, in order to establish\nsuch a guideline, we investigate the convergence behavior of the main\nTDDMRG simulation parameters, such as time integrator, the choice\nof orbitals, and the choice of matrix-product-state representation\nfor complex-valued nonsinglet states. In addition, we propose a method\nto select orbitals that are tailored to optimize the dynamics. Lastly,\nwe showcase the TDDMRG by applying it to charge migration ionization\ndynamics in furfural, where we reveal a rapid conversion from an ionized\nstate with a σ character to one with a π character within\nless than a femtosecond.