Extended ab initio quantum mechanical/molecular mechanical molecular dynamics simulations of hydrated Cu2+

Abstract

Articles you may be interested inDynamics of ligand exchange mechanism at Cu(II) in water: An ab initio quantum mechanical charge field molecular dynamics study with extended quantum mechanical region Structural and dynamical properties of Co(III) in aqueous solution: Ab initio quantum mechanical/molecular mechanical molecular dynamics simulation Copper͑II͒ was used as a model system to investigate the relevance of including the full second hydration shell in ab initio treatment while describing hydrated ions in hybrid quantum mechanical/ molecular mechanical molecular dynamics ͑QM/MM MD͒ simulations. Three different simulation techniques were applied ͑Hartree-Fock, B3LYP, and resolution of the identity density functional theory͒ to find a good compromise between accuracy and simulation speed. To discuss details of the hydration structure radial distribution functions, coordination number distributions and various angular distributions have been used. Dynamical properties such as vibrational motions of water molecules and ion-oxygen stretching motions were investigated using approximative normal coordinate analyses. QM/MM MD simulations offer a detailed time picture of the dynamic Jahn-Teller effect of Cu 2ϩ showing short-term as well as long-term distortions to occur within Ͻ200 fs and 2-3 ps. The results prove that for transition metal ions such as Cu 2ϩ the inclusion of the second shell into the ab initio treated region can be of decisive importance for obtaining accurate results and that such simulations can offer new insights into chemical dynamics on the picosecond scale.

Absolute proton hydration free energy, surface potential of water, and redox potential of the hydrogen electrode from first principles: QM/MM MD free-energy simulations of sodium and potassium hydration

“…[313][314][315] However, in view of the on-going development of more efficient QM algorithms 179,[316][317][318][319] in conjunction with the use of graphics processing units 124,318,320,321 (GPUs), this limitation may be overcome in the near future. The calculation for anions is of particular interest considering that the accurate calculation of salt (cation plus anion) hydration free energies, which are not elusive quantities (just as the cation-to-cation difference considered here), would represent an important further validation of the present QM/MM methodology.…”

Hydration of Copper(II): New Insights from Density Functional Theory and the COSMO Solvation Model

“…[14][15][16][17][18][19][20][31][32][33][34][35][36][37] Our calculations favor Cu(II)-water complexes with first-shell coordination number of five for clustes with eight to ten water molecules. Note the results of solvation calculations are sensitive to the selection of the copper solvation radius when Cu(II) ions are in contact with the solvent dielectric boundary.…”

“…Conversely, calculations with a basis set of double-quality with no diffuse functions (LANL2DZ/6-31G**) reduce this difference to only 0.3 kcal/mol. A basis set of similar quality (LANL2DZ/DZP) has been employed previously [34][35][36][37] in the QM/MM molecular dynamics simulations of hydrated Cu 2+ . Because small basis sets might not be sufficient to correctly describe the Cu 2+ /H 2 O systems, the reported fully atomistic QM/MM calculations 34-37 predicting 6-fold coordinated geometry of Cu 2+ in water might need to be validated using more extended basis sets.…”

“…[1][2][3][4][5] Detailed information on ligands arrangement around the Cu(II) ion is only available in the solid state [6][7][8][9][10][11][12][13] whereas the structural information in the aqueous phase [13][14][15][16][17][18][19][20] is less definitive and available only for few Cu 2+ complexes. Although static [20][21][22][23][24][25][26][27][28][29][30] and dynamic [31][32][33][34][35][36][37] electronic structure calculations can, in principle, provide such information, realistic modeling of Cu(II) complexes in aqueous solution with highly flexible coordination environment still remains a challenge. Classical force field simulations [even with three-body potential functions 35 ] do not provide good alternatives to electronic structure calculations in this case, as they fail to describe the Jahn-Teller distortion around the aqueous Cu 2+ ion unless explicit ligand field correction terms stabilizing the distorted octahedral Cu(II)-water clusters are employed.…”

“…31,32 In contrast, QM/ MM MD simulations [employing HF, B3LYP, and MP2 levels of theory with the double-valence basis set for water and the comparable LANL2DZ basis set for Cu 2+ ] resulted in predicting exclusively the Jahn-Teller distorted 6-fold coordinated species. [34][35][36][37] A study of the hydration of Cu 2+ by a small number of water molecules may be an important step toward a better understanding of peculiar solvation effects in bulk water. Electronic structure calculations and mass-spectrometric analysis provide convenient tools for studying metal ion-H 2 O clusters 44 in the gas phase.…”