Aqueous Solvation of SmI2: A Born-Oppenheimer Molecular Dynamics Density Functional Theory Cluster Approach - INSA Toulouse - Institut National des Sciences Appliquées de Toulouse Access content directly
Journal Articles Journal of Physical Chemistry A Year : 2017

Aqueous Solvation of SmI2: A Born-Oppenheimer Molecular Dynamics Density Functional Theory Cluster Approach

Abstract

We report the results of Born-Oppenheimer molecular dynamics (BOMD) simulations on the aqueous solvation of the SmI2 molecule at room temperature using the cluster microsolvation approach including 32 water molecules. The electronic structure calculations were done using the M062X hybrid exchange-correlation functional in conjunction with the 6-31G** basis sets for oxygen and hydrogen. For the iodine and samarium atoms the Stuttgart Koln relativistic effective core potentials were utilized with their associated valence basis sets. Starting from the optimized geometry of SmI2 embeded in the microsolvation environment, we find a swift substitution of the iodine ions by eight tightly bound water molecules around Sm(II). Through the Sm-O radial distribution function and the evolution of the Sm-O distances, the present study predicts a first rigid Sm(II) solvation shell from 2.6,to 3.4 (A) over circle, whose integration leads to a coordination number of 8.4 water molecules, and a second softer solvation sphere from 3.5 to ca. 6 (A) over circle. The Sm(II)-O radial distribution function is in excellent agreement with that reported for Sr2+ from:EXATS studies, a fact that can be explained because Sr2+ and Sm2+ have almost identical ionic radii (ca. 1.26 (A) over circle) and coordination numbers: 8 for Sr2+ and 8.4 for Sm2+. The theoretical EXAFS spectrum was obtained from the BOMD trajectory and is discussed in the light ofthe experimental spectra for Sm(III). Once microsolvation is achieved, no water exchange events were found to occur around Sm2+, in agreement with the experimental data for Eu2+ (which has a nearly identical charge-to-ionic radius relation as Sm2+),-where the mean residence time of a water molecule in [Eu(H2O)(8)](2+) is known to be ca. 230 ps.
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Dates and versions

hal-01961176 , version 1 (19-12-2018)

Identifiers

  • HAL Id : hal-01961176 , version 1

Cite

A. Ramirez-Solis, J. I. Amaro-Estrada, J. Hernandez-Cobos, Laurent Maron. Aqueous Solvation of SmI2: A Born-Oppenheimer Molecular Dynamics Density Functional Theory Cluster Approach. Journal of Physical Chemistry A, 2017, 121 (11), pp.2293--2297. ⟨hal-01961176⟩
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