Explicitly time-dependent coupled cluster singles doubles calculations of laser-driven many-electron dynamics

Area of Science:

• Quantum Chemistry
• Computational Molecular Science
• Laser-Matter Interactions

Background:

• Accurately simulating laser-driven electron dynamics in molecules is crucial for understanding photochemical processes.
• Existing methods often struggle with the complexity of correlated many-electron systems under intense laser fields.

Purpose of the Study:

• To develop and apply explicitly time-dependent coupled cluster singles doubles (TD-CCSD) calculations for simulating molecular dynamics.
• To investigate the accuracy and numerical stability of the TD-CCSD method for small molecules (HF, H2O, NH3, CH4) under laser excitation.

Main Methods:

• Utilized time-dependent coupled cluster singles doubles (TD-CCSD) calculations.
• Employed polarized valence double zeta basis sets for small molecular systems.
• Determined ground states via imaginary time propagation.
• Calculated excited state energies from the Fourier transform of time-dependent dipole moments following ultrashort laser excitation.
• Computed time-dependent expectation values from complex cluster amplitudes and configuration interaction singles doubles wave functions.

Main Results:

• Successfully simulated laser-driven correlated many-electron dynamics in HF, H2O, NH3, and CH4.
• Obtained excited state energies by analyzing the time-dependent dipole moment.
• Explored resonant laser excitations and assessed the numerical stability of the TD-CCSD implementation.

Conclusions:

• The TD-CCSD method provides a robust framework for simulating laser-induced molecular dynamics.
• The implementation demonstrates potential for exploring complex electron correlation effects in excited states.
• Further development is needed to address numerical stability challenges in simulating resonant excitations.