Improving Vibrational Mode Interpretation Using Bayesian Regression

Abstract

To streamline the interpretation of vibrational spectra, this work introduces the use of Bayesian linear regression with automatic relevance determination as a viable approach to decompose the atomic motions along any vibrational mode as a weighted combination of displacements along chemically meaningful internal coordinates. This novel approach denominated vibrational mode automatic relevance determination (VMARD) is presented and compared with the well-established potential energy decomposition (PED) scheme. Good agreement is generally attained between the two methods. VMARD returns a decomposition of the atomic displacement using only a small number of internal coordinates, thus aiding the interpretation of the vibrational spectra. Moreover, the results show that the VMARD descriptions are resilient toward the addition of additional internal coordinates, achieving a concise description of the vibrational modes despite the use of redundant internal coordinates. Potential applications of VMARD involving the gathering of physical insights on the atomic motions along the reaction coordinate at transition state structures, as well as the improvement of theoretically predicted vibrational frequencies, are also presented under a proof-ofconcept perspective.

Conformational Space, IR-Induced, and UV-Induced Chemistry of Carvacrol Isolated in a Low-Temperature Argon Matrix

“…The theoretical IR spectra of the different species were simulated by using Chemcraft software (version 1.8). 56 The B3LYP/6-311++G(d,p)-calculated harmonic wavenumbers were scaled by 0.980 in the spectral region below 2000 cm −1 . Due to the larger anharmonicity of the higherfrequency vibration modes, two additional scale factors were used for achieving better agreement between the experimental and theoretical spectra: 0.960 (between 3200 and 2000 cm −1 ) and 0.950 (above 3200 cm −1 ).…”

Anharmonic quantum nuclear densities from full dimensional vibrational eigenfunctions with application to protonated glycine

“…Instead, chemical intuition is tempted to assert that a given vibrational normal mode is only weakly coupled to other modes in faraway parts of the molecule [11][12][13] , so that distance-based truncation of couplings is a common view in chemistry. Consequently, many methods have been proposed to localize normal modes 12,[14][15][16][17][18] , to help with the interpretation of spectra in terms of chemically intuitive motions also for large systems.…”

Computational Exploration of Spectroscopic and Hydrogen Bonding Analysis of Direct Orange 26 Dye in Combination with Experimental and TD-DFT Calculations.

“…The VMD 1.9 program [33] has been used for rendering the color mapped isosurface graphs of electrostatic potential (ESP) of the ground states of the studied dye; based on the data outputted by Multiwfn program. The VibAnalysis code [34,35] with corresponding to VEDA program [36] has been used for calculation of the potential energy distribution (PED) for various vibrational normal modes of the studied DO-26 dye (D1).…”

“…All the vibrational modes are properly assigned applying the basis of PED. By using free VibAnalysis code [34,35] with corresponding to VEDA program [36]; the various vibrational normal modes have been calculated. The calculated FTIR frequency intensities and assignments listed in Table 3; are selected in normal modes up to 400 cm -1 .…”