Al3+, Ca2+, Mg2+, and Li+ in aqueous solution: Calculated first-shell anharmonic OH vibrations at 300 K
2010 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 133, no 17, 174513- p.Article in journal (Refereed) Published
The anharmonic OH stretching vibrational frequencies, nu(OH), for the first-shell water molecules around the Li+, Ca2+, Mg2+, and Al3+ ions in dilute aqueous solutions have been calculated based on classical molecular dynamics (MD) simulations and quantum-mechanical (QM) calculations. For Li+(aq), Ca2+(aq), Mg2+(aq), and Al3+(aq), our calculated IR frequency shifts, Delta nu(OH), with respect to the gas-phase water frequency, are about -300, -350, -450, and -750 cm(-1), compared to -290, -290, -420, and -830 cm(-1) from experimental infrared (IR) studies. The agreement is thus quite good, except for the order between Li+ and Ca2+. Given that the polarizing field from the Ca2+ ion ought to be larger than that from Li+(aq), our calculated result seems reasonable. Also the absolute OH frequencies agree well with experiment. The method we used is a sequential four-step procedure: QM(electronic) to make a force field+MD simulation +QM(electronic) for point-charge-embedded Mn+ (H2O)(x)(first shell) (H2O)(y)(second shell) (H2O)(z)(third shell) clusters+QM(vibrational) to yield the OH spectrum. The many-body Ca2+-water force-field presented in this paper is new. IR intensity-weighting of the density-of-states frequency distributions was carried out by means of the squared dipole moment derivatives.
Place, publisher, year, edition, pages
2010. Vol. 133, no 17, 174513- p.
aluminium, calcium, infrared spectra, lithium, magnesium, molecular dynamics method, positive ions, solvation, solvent effects, vibrational states, water
Research subject Chemistry with specialization in Inorganic Chemistry
IdentifiersURN: urn:nbn:se:uu:diva-135346DOI: 10.1063/1.3460261ISI: 000283936200059OAI: oai:DiVA.org:uu-135346DiVA: diva2:375468