High harmonic spectra computed using time-dependent Kohn-Sham theory with Gaussian orbitals and a complex absorbing...

Area of Science:

• Computational physics
• Quantum chemistry
• Strong-field physics

Background:

• Simulating high harmonic generation (HHG) in molecules is crucial for understanding light-matter interactions.
• Existing methods face challenges with basis set limitations and spurious wave packet reflections.
• Accurate spectral resolution is essential for interpreting HHG data.

Purpose of the Study:

• To develop and validate a computational method for simulating high harmonic spectra of H2 and H2+.
• To mitigate artifacts arising from finite basis sets in time-dependent calculations.
• To demonstrate the efficacy of an atom-centered absorbing potential for spectral accuracy.

Main Methods:

• Solving the time-dependent Kohn-Sham equation with an atom-centered Gaussian basis set.
• Employing a complex absorbing potential to absorb outgoing electronic wave packets.
• Analyzing high harmonic spectra for H2 and H2+ under strong laser fields.

Main Results:

• The atom-centered absorbing potential effectively suppresses spurious reflections and artifacts.
• Well-resolved high harmonic spectra were obtained, showing improved accuracy.
• The method demonstrated potential for extension to larger molecular systems.

Conclusions:

• Atom-centered absorbing potentials are effective for accurate HHG spectral simulations.
• This approach offers advantages over grid-based methods, particularly for larger molecules.
• The developed method enhances the reliability of theoretical predictions in strong-field physics.