Harmonic Infrared and Raman Spectra in Molecular Environments Using the Polarizable Embedding Model.

Area of Science:

• Computational chemistry
• Spectroscopy
• Quantum mechanics

Background:

• Calculating molecular spectra in complex environments is challenging.
• Existing methods often lack accuracy for condensed-phase systems.
• The polarizable embedding (PE) model offers a way to represent molecular environments.

Purpose of the Study:

• To develop a fully analytic approach for calculating IR and Raman spectra of molecules within the PE model.
• To enable accurate vibrational spectroscopy of molecules in complex, realistic environments.
• To provide a theoretical framework extendable to higher-order derivatives.

Main Methods:

• Analytic calculation of second-order geometric energy derivatives and first-order dipole moment/polarizability derivatives within the PE model.
• Implementation using a general open-ended response theory framework.
• Derivation of embedding-potential parameters from first-principles calculations.

Main Results:

• Demonstrated proof-of-principle calculations for IR and Raman spectra of acetone in various solvents.
• Validated the analytic approach for vibrational spectra prediction in condensed phases.
• Established a robust theoretical framework for PE model applications.

Conclusions:

• The developed analytic approach is a significant advancement for calculating vibrational spectra of molecules in complex environments.
• This method paves the way for accurate spectroscopic predictions in realistic chemical systems.
• The framework supports diverse applications, including solvents and biological molecules.