State-specific vibration correlation methods beyond the vibrational multi-configuration self-consistent field (VMCSCF) approximation have been developed, which allow for the accurate calculation of state energies for systems suffering from strong anharmonic resonances. Both variational multi-reference configuration interaction approaches and an implementation of approximate 2nd order vibrational multi-reference perturbation theory are presented. The variational approach can be significantly accelerated by a configuration selection scheme, which leads to negligible deviations in the final results. Relaxation effects due to the partitioning of the correlation space and the performance of a VMCSCF modal basis in contrast to a standard modal basis obtained from vibrational self-consistent field theory have been investigated in detail. Benchmark calculations based on high-level potentials are provided for the propargyl cation and cis-diazene.
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http://dx.doi.org/10.1063/1.4865098 | DOI Listing |
Sci Rep
December 2024
Department of Chemistry, Faculty of Science, K. N. Toosi University of Technology, P.O. Box 15875-4416, Tehran, Iran.
This research presents an innovative approach for synthesizing 2-amino-4H-chromene derivatives, utilizing 30 mg of NS-doped graphene oxide quantum dots (GOQDs) as a catalyst in a one-pot, three-component reaction conducted in ethanol. The NS-doped GOQDs were synthesized using a cost-effective bottom-up method through the condensation of citric acid (CA) with thiourea and the reaction was carried out at 185 C, resulting in the elimination of water. The catalytic performance of the synthesized NS-doped GOQDs resulted in high product yields, achieving up to 98% for the 2-amino-4H-chromene derivatives from aromatic aldehydes, malononitrile, resorcinol, -naphthol, and dimedone.
View Article and Find Full Text PDFJACS Au
December 2024
Freie Universität Berlin, Physics Department, Experimental Molecular Biophysics, Arnimallee 14, 14195 Berlin, Germany.
Vibrational Stark effect (VSE) spectroscopy has become one of the most important experimental approaches to determine the strength of noncovalent, electrostatic interactions in chemistry and biology and to quantify their influence on structure and reactivity. Nitriles (C≡N) have been widely used as VSE probes, but their application has been complicated by an anomalous hydrogen bond (HB) blueshift which is not encompassed within the VSE framework. We present an empirical model describing the anomalous HB blueshift in terms of H-bonding geometry, i.
View Article and Find Full Text PDFSci Rep
December 2024
School of Civil Engineering, Liaoning Technical University, Fuxin, 123000, China.
Blasting excavation is widely used in mining, tunneling and construction industries, but it leads to produce ground vibration which can seriously damage the urban communities. The peak particle velocity (PPV) is one of main indicators for determining the extent of ground vibration. Owing to the complexity of blasting process, there is controversy over which parameters will be considered as the inputs for empirical equations and machine learning (ML) algorithms.
View Article and Find Full Text PDFJ Phys Chem B
December 2024
Research Institute of Interdisciplinary Science & School of Materials Science and Engineering, Dongguan University of Technology, Dongguan 523808, China.
Peptide-based hydrogels form a kind of promising material broadly used in biomedicine and biotechnology. However, the correlation between their hydrogen bonding dynamics and mechanical properties remains uncertain. In this study, we found that the adoption of β-sheet and α-helix secondary structures by ECF-5 and GFF-5 peptides, respectively, could further form fiber networks to immobilize water molecules into hydrogels.
View Article and Find Full Text PDFErgonomics
December 2024
Department of Mechanical Engineering, Politecnico di Milano, Lecco, Italy.
Supine postures are increasingly adopted in medical transport, long-duration flights, and other healthcare environments. This study is aimed to identify the effect of vibration direction and magnitude on the objective and subjective responses of the human body in a supine posture. The transmissibilities to the head, chest, abdomen, and thighs of 12 male subjects were measured with single-axis random vibrations in longitudinal ( axis), lateral ( axis), and vertical ( axis) direction at 0.
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