Ab initio computed interaction forces are employed to describe the microsolvation of the A+2(2Sigma) (A=Li, Na, K) molecular ion in 4He clusters of small variable size. The minimum energy structures are obtained by performing energy minimization based on a genetic algorithm approach. The symmetry features of the collocation of solvent adatoms around the dimeric cation are analyzed in detail, showing that the selective growth of small clusters around the two sides of the ion during the solvation process is a feature common to all three dopants.
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http://dx.doi.org/10.1021/jp0748361 | DOI Listing |
ACS Omega
December 2024
Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México.
Born-Oppenheimer molecular dynamics (BOMD) simulations were performed to investigate the structure and dynamics of the first hydration shells of five trivalent lanthanide ions (Ln) at room temperature. These ions are relevant in various environments, including the bulk aqueous solution. Despite numerous studies, accurately classifying the molecular geometry of the first hydration sphere remains a challenge.
View Article and Find Full Text PDFPhys Chem Chem Phys
September 2023
Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark.
Radiation damage in biological systems by ionizing radiation is predominantly caused by secondary processes such as charge and energy transfer leading to the breaking of bonds in DNA. Here, we study the fragmentation of cytosine (Cyt) and thymine (Thy) molecules, clusters and microhydrated derivatives induced by direct and indirect ionization initiated by extreme-ultraviolet (XUV) irradiation. Photofragmentation mass spectra and photoelectron spectra of free Cyt and Thy molecules are compared with mass and electron spectra of Cyt/Thy clusters and microhydrated Cyt/Thy molecules formed by aggregation in superfluid helium (He) nanodroplets.
View Article and Find Full Text PDFJ Chem Phys
August 2023
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
Intermolecular Coulombic decay or electron transfer-mediated decay are the autoionization processes through which a molecule can relax. This relaxation is only possible if the inner valence's ionization potential (IP) exceeds the system's double ionization potential (DIP). To study the effects of charge and solvation shell, we have calculated the IP, DIP values, and lifetime of Na-2s and Mg-2s temporary bound states in various optimized structures of Na+-(H2O)n and Mg2+-(H2O)n (n = 1-5) micro-solvated clusters, where n water molecules are distributed in a way that some are directly bound to the metal ion and the rest to the water molecules.
View Article and Find Full Text PDFJ Phys Chem A
August 2023
Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States.
The infrared predissociation spectra of the GlyH(HO) and AlaH(HO) clusters are presented and analyzed with the goal of revealing the influence of methyl side chains on the microsolvated structures of these flexible tripeptides. We have shown previously that the presence of methyl side chains can modulate the strengths of the intramolecular hydrogen bonds, thereby influencing the structures adopted by the bare tripeptides composed of glycine and alanine residues. This effect was attributed to the electron-donating nature of the methyl group, whose presence alters the proton affinities of the functional groups that are involved in hydrogen bonding.
View Article and Find Full Text PDFJ Comput Chem
September 2023
Université de Lorraine and CNRS, Laboratoire de Physique et Chimie Théoriques UMR 7019, Nancy, France.
The presence of carboxyl groups in a molecule delivers an affinity to metal cations and a sensitivity to the chemical environment, especially for an environment that can give rise to intermolecular hydrogen bonds. Carboxylate groups can also induce intramolecular interactions, such as the formation of hydrogen bonds with donor groups, leading to an impact on the conformational space of biomolecules. In the latter case, the protonation state of the amino groups plays an important role.
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