Scaling-up VPT2: A feasible route to include anharmonic correction on large molecules

Year: 2024

Authors: Fusi M., Mazzeo G., Longhi G., Abbate S., Yang Q., Bloino J.

Autors Affiliation: Univ Brescia, Dipartimento Med Mol & Traslazionale, Viale Europa 11, I-25123 Brescia, Italy; Ist Nazl Ott INO, Res Unit Brescia, CNR, CSMT, VIA Branze 45, I-25123 Brescia, Italy; Czech Acad Sci, Inst Organ Chem & Biochem, Flemingovo Namesti 542-2, Prague 16000, Czech Republic; Scuola Normale Super Pisa, Piazza Cavalieri, I-56125 Pisa, Italy.

Abstract: Vibrational analysis plays a crucial role in the investigation of molecular systems. Though methodologies like second -order vibrational perturbation theory (VPT2) have paved the way to more accurate simulations, the computational cost remains a difficult barrier to overcome when the molecular size increases. Building upon recent advances in the identification of resonances, we propose an approach making anharmonic simulations possible for large -size systems, typically unreachable by standard means. This relies on the fact that, often, only portions of the whole spectra are of actual interest. Therefore, the anharmonic corrections can be included selectively on subsets of normal modes directly related to the regions of interest. Starting from the VPT2 equations, we evaluate rigorously and systematically the impact of the truncated anharmonic treatment onto simulations. The limit and feasibility of the reduced -dimensionality approach are detailed, starting on a smaller model system. The methodology is then challenged on the IR absorption and vibrational circular dichroism spectra of an organometallic complex in three different spectral ranges.

Journal/Review: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY

Volume: 311      Pages from: 123969-1  to: 123969-18

More Information: MF would like to thank professor Edoardo Cesarotti. The study of the chiral transition metal complexes that are investigated here began with him. Funding was provided by the Italian Ministry of University and Research (MUR) through the PRIN program (PRIN 2017, project Physico-chemical Heuristic Approaches: Nanoscale Theory of Molecular Spectroscopy (PHANTOMS) , prot. 2017A4XRCA; PRIN 2020, project Photoreactive Systems upon Irradiation: Modelling and Observation of Vibrati onal Interactions with the Environment’’ (PSI-MOVIE) , prot. 2020HTSXMA; PRIN 2022, project Enhancing Circu-larly Polarised Emitters Quantum Efficiency Exploiting Singlet-Triplet Inversion (INVESTCPE) , prot. 2022CXHY3 A) . Computing facilities from SNS HPC are acknowledged.
KeyWords: Vibrational circular dichroism (VCD); Anharmonicity; Second-order vibrational perturbative theory (VPT2); Reduced-dimensionality; Ruthenium complexes
DOI: 10.1016/j.saa.2024.123969

Citations: 7
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