How Reliable Are Modern Density Functional Approximations to Simulate Vibrational Spectroscopies?
Sebastian P Sitkiewicz1,2, Robert Zaleśny3, Eloy Ramos-Cordoba1,2
1Donostia International Physics Center (DIPC), 20018 Donostia, Euskadi, Spain.
The Journal of Physical Chemistry Letters
|June 23, 2022
Summary
Density functional approximations (DFAs) can cause errors in molecular property calculations, especially for low-frequency modes. LC-BLYP and BH&H functionals show robustness against these spurious oscillations.
Area of Science:
- Computational chemistry
- Quantum chemistry
- Spectroscopy
Background:
- Density functional approximations (DFAs) are widely used for calculating molecular properties.
- Low-frequency modes in molecules can be susceptible to numerical integration errors.
- These errors can lead to spurious oscillations in calculated properties.
Purpose of the Study:
- To identify and quantify errors in DFAs caused by spurious oscillations in low-frequency modes.
- To evaluate the robustness of various DFAs against these errors.
- To provide guidance on the reliable use of DFAs in vibrational spectroscopy.
Main Methods:
- Fourier spectral analysis
- Digital signal processing techniques
- Calculation of energy, dipole moment, and polarizability derivatives for 45 DFAs.
- Assessment of molecular properties for molecules with low-frequency modes.
Main Results:
- Spurious oscillations due to numerical integration errors affect DFA calculations of molecules with low-frequency modes.
- These oscillations lead to significant errors in IR and Raman intensities and frequencies.
- LC-BLYP and BH&H were the only functionals found to be robust against these spurious oscillations.
Conclusions:
- Modern DFAs should be used with caution for simulating vibrational spectroscopies due to potential errors from spurious oscillations.
- The identified robust functionals (LC-BLYP, BH&H) offer reliable alternatives for such calculations.
- Understanding and mitigating numerical errors is crucial for accurate computational chemistry predictions.
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