Workflow for Harmonic IR and Raman Spectra of Embedded Systems: The PE-QM Approach.

Area of Science:

• Computational Chemistry
• Spectroscopy
• Physical Chemistry

Background:

• Accurate simulation of molecular spectra in solution is crucial for understanding chemical processes.
• Multiscale modeling approaches are needed to balance accuracy and computational cost.
• Polarizable embedding methods offer a promising route for QM/MM simulations.

Purpose of the Study:

• To present a comprehensive workflow for simulating harmonic IR and Raman spectra of solute-solvent systems using a polarizable embedding quantum mechanics (PE-QM) approach.
• To establish benchmarks and evaluate the accuracy and limitations of the PE-QM method for spectral simulations.
• To demonstrate the applicability of the workflow through simulations of acetone in various solvents.

Main Methods:

• A multiscale modeling scheme dividing the system into a quantum mechanical core and a polarizable embedding environment.
• Workflow encompassing structure generation, property calculation, and data postprocessing.
• Benchmark calculations to assess approximation errors and method performance.

Main Results:

• The PE-QM workflow provides a roadmap for simulating solute-solvent spectra.
• Benchmark calculations quantified errors and highlighted strengths and weaknesses of the approach.
• Simulations of acetone in three solvents showed good agreement with experimental spectra, validating the method.

Conclusions:

• The presented PE-QM workflow is a valuable tool for simulating IR and Raman spectra of solute-solvent systems.
• The approach demonstrates accuracy and provides insights into the strengths and limitations of polarizable embedding methods.
• This work represents a significant step towards modeling more complex molecular systems with fragment-based PE approaches.