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

0582939 - ÚOCHB 2025 RIV GB eng J - Journal Article
Fusé, M. - Mazzeo, G. - Longhi, G. - Abbate, S. - Yang, Qin - Bloino, J.
Scaling-up VPT2: A feasible route to include anharmonic correction on large molecules.
Spectrochimica Acta Part A-Molecular and Biomolecular Spectroscopy. Roč. 311, April (2024), č. článku 123969. ISSN 1386-1425. E-ISSN 1873-3557
Institutional support: RVO:61388963
Keywords : vibrational circular dichroism (VCD) A * anharmonicity * second-order vibrational perturbative theory * (VPT2) * reduced-dimensionality * ruthenium complexes
Impact factor: 4.4, year: 2022
Method of publishing: Open access
https://doi.org/10.1016/j.saa.2024.123969

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.
Permanent Link: https://hdl.handle.net/11104/0350985