Tailored anharmonic potential energy surfaces for infrared signatures
Janine Hellmers1, Pascal Czember1, Carolin König1
1Institut of Physical Chemistry and Electrochemistry, Leibniz University Hannover, Germany. carolin.koenig@pci.uni-hannover.de.
Physical Chemistry Chemical Physics : PCCP
|December 2, 2024
Summary
Calculating vibrational spectra is crucial for experiments. This study introduces a new computational protocol for accurate and efficient anharmonic vibrational structure calculations, focusing on key molecular vibrations.
Area of Science:
- Computational Chemistry
- Spectroscopy
- Quantum Mechanics
Background:
- Accurate infrared spectra are vital for interpreting experimental data.
- Full-space anharmonic vibrational calculations are computationally expensive and limited in scope.
- Specific molecular vibrations often dominate spectral signatures.
Purpose of the Study:
- To develop a computational protocol for accurate and efficient anharmonic vibrational spectra calculations.
- To tailor high-dimensional anharmonic potential energy surfaces for key vibrational modes.
- To support experimental interpretation through precise spectral signature calculations.
Main Methods:
- Proposing a computational protocol using vibrational coupled cluster response theory.
- Tailoring high-dimensional anharmonic potential energy surfaces.
- Selecting appropriate coordinates and mode-coupling terms for relevant degrees of freedom.
- Applying varying levels of electronic structure theory and restricted higher mode-coupling terms.
- Validating the protocol on C=O stretching in uracil and OH stretching in catechol.
Main Results:
- The FALCON algorithm's convergence behavior indicates the locality of degrees of freedom.
- Normal coordinates effectively described C=O stretching in uracil.
- Local FALCON coordinates provided superior performance for OH stretching in catechol.
- The protocol enables accurate and efficient anharmonic calculations of vibrational spectral signatures.
Conclusions:
- The developed protocol offers effective guidelines for computational vibrational spectroscopy.
- The choice of coordinates (normal vs. local) is crucial and system-dependent.
- This approach enhances the feasibility of accurate anharmonic calculations for complex molecules.
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