2-in-1 Phase Space Sampling for Calculating the Absorption Spectrum of the Hydrated Electron.

Area of Science:

• Computational chemistry
• Quantum mechanics
• Spectroscopy

Background:

• Vibrational effects on absorption spectra are crucial but challenging to model.
• Traditional methods like Wigner and thermal sampling have limitations for flexible or anharmonic systems.
• Nuclear quantum effects (NQEs) significantly impact spectroscopic properties, especially for hydrogen atoms, but are often neglected.

Purpose of the Study:

• To introduce and validate generalized smoothed trajectory analysis (GSTA) as a postprocessing method for incorporating NQEs.
• To compute the absorption spectrum of a hydrated electron and related systems, accounting for NQEs.
• To investigate the influence of NQEs on the energetic and structural properties of excess electrons in water systems.

Main Methods:

• Employed generalized smoothed trajectory analysis (GSTA) to postprocess classical trajectories.
• Utilized mixed classical-quantum simulations to generate structures for water cluster anions and the hydrated electron.
• Filtered classical trajectories to incorporate quantum effects of atomic nuclei.
• Calculated absorption spectra at various theoretical levels.

Main Results:

• Demonstrated that GSTA successfully integrates NQEs, overcoming limitations of Wigner and thermal sampling.
• Observed significant NQEs in the absorption spectra of hydrated electron systems.
• Results showed a notable red shift and broadening of spectra due to NQEs.
• Provided insights into the energetic and structural properties influenced by NQEs.

Conclusions:

• GSTA is a versatile and applicable method for complex systems requiring NQEs.
• NQEs play a critical role in accurately predicting the absorption spectra of hydrated electrons.
• The study highlights the importance of considering nuclear quantum effects in theoretical spectroscopy.