Sequential double ionization of molecules by strong laser fields simulated with time-dependent configuration...

Area of Science:

• Quantum Chemistry
• Strong Field Physics
• Molecular Dynamics

Background:

• Simulating strong field sequential double ionization (SFDI) of molecules is computationally challenging.
• Accurate theoretical methods are needed to understand electron dynamics during intense laser-matter interactions.

Purpose of the Study:

• To develop and implement a novel time-dependent configuration interaction (TDCI) method for simulating SFDI.
• To investigate the sequential ionization dynamics of HBr and HI molecules under intense laser pulses.

Main Methods:

• A two-step TDCI approach combining time-dependent configuration interaction with single excitations (TD-CIS) for the first ionization and a CISD-IP wavefunction for the second ionization.
• Wavefunction transfer between simulations achieved via ionization rate partitioning or singular value decomposition (SVD).
• Simulations performed for HBr and HI using specific laser pulse parameters (wavelength, polarization, intensity, duration).

Main Results:

• The developed TDCI method successfully simulates sequential double ionization.
• SVD analysis reveals a dominant component for the cation wavefunction after the first ionization.
• Simulations show cation population dynamics (rise and fall) during ionization to the dication.
• For HI with circularly polarized light, ionization rates peak when the electric field aligns with the pπ orbital.

Conclusions:

• The new TDCI method provides an accurate and efficient way to study SFDI in molecules.
• The findings offer insights into the complex electron dynamics governing molecular ionization under strong laser fields.
• Understanding these dynamics is crucial for applications in attosecond science and laser-driven chemistry.