Vibrational intensities in the mobile block Hessian approximation.
Richard Terrett1, Rob Stranger1, Terry Frankcombe2
1Research School of Chemistry, Australian National University, Canberra, Australia. rob.stranger@anu.edu.au.
Physical Chemistry Chemical Physics : PCCP
|February 18, 2017
Summary
This study introduces a new method to calculate molecular vibrational intensities using density functional theory and the Mobile Block Hessian approximation. This approach offers a computationally efficient way to analyze specific molecular regions.
Area of Science:
- Computational Chemistry
- Molecular Spectroscopy
- Quantum Chemistry
Background:
- Vibrational intensity calculations are crucial for interpreting experimental spectra.
- Traditional methods can be computationally expensive, especially for large molecules.
- The Mobile Block Hessian (MBH) approximation offers a way to simplify calculations by constraining molecular subsets.
Purpose of the Study:
- To present a proof of concept for recovering vibrational intensities using the MBH approximation.
- To evaluate the accuracy and performance of the MBH method compared to conventional calculations.
- To explore the impact of constrained region size on accuracy.
Main Methods:
- Density functional theory (DFT) vibrational calculations.
- Implementation of the Mobile Block Hessian (MBH) approximation.
- Comparison of MBH results with conventional all-atom calculations across various molecules.
Main Results:
- Successful recovery of vibrational intensities from MBH-approximated calculations.
- Demonstrated viability of the MBH method for targeted vibrational analysis.
- Characterized performance and accuracy relative to MBH region size and molecular species.
Conclusions:
- The MBH approximation provides a computationally efficient route to obtain vibrational intensities for specific molecular regions.
- This method can significantly reduce computational cost compared to full calculations.
- Caveats for the application of this method are discussed.
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