Simulating Electron Dynamics of Complex Molecules with Time-Dependent Complete Active Space Configuration...

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• Time-dependent electronic structure methods are crucial for modeling ultrafast phenomena and spectra.
• Time-dependent configuration interaction (TD-CI) offers advantages over time-dependent density functional theory, including accurate Rabi oscillation modeling and spin-pure descriptions.
• Existing TD-CI methods face scalability challenges for large systems.

Purpose of the Study:

• To present a novel TD-CI approach extending its application to large complete active-space expansions.
• To enable efficient and accurate simulations of complex molecular systems and their response to light.
• To overcome the computational limitations of traditional TD-CI methods.

Main Methods:

• A direct configuration interaction approach was implemented, avoiding explicit Hamiltonian matrix construction and diagonalization.
• Graphics processing unit (GPU) acceleration was utilized for fast computation of the time-dependent Schrödinger equation (TDSE).
• A symplectic split operator propagator was employed for long-time norm conservation in simulations.

Main Results:

• The novel TD-CI approach successfully modeled the response of decacene (C42H24), a molecule with a strongly correlated ground state, to various laser pulses.
• Simulations predicted that chirped pulses can induce dipole-forbidden transitions in decacene.
• The method achieved accurate long-time propagation (100 fs) with a 1 as time step on a single GPU for a large active space (12 electrons/12 orbitals).

Conclusions:

• The developed direct TD-CI method offers a scalable and accurate approach for electronic structure calculations.
• This method enables the study of complex light-matter interactions and the prediction of novel spectroscopic phenomena.
• The computational efficiency and accuracy make it a valuable tool for investigating strongly correlated systems and designing advanced optical control strategies.