An extended <i>ab initio</i> QM/MM MD approach to structure and dynamics of Zn(II) in aqueous solution

Fatmi, M. Qaiser; Hofer, Thomas S.; Randolf, Bernhard R.; Rode, Bernd M.

doi:10.1063/1.1996575

Cited by 70 publications

(53 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…basis quality). 13,14,16 With increasing computational resources, larger systems were simulated using classical, 11,17,18 hybrid (QM/MM) [19][20][21] and DFT 2 based 22,23 molecular dynamics (MD) and pointed to a Zn coordination number of 6, consistent with experimental observations. However, a recent theoretical investigation of aqueous Zn coordination, 24 using the GGA-BLYP functional and based on a thermodynamic integration of forces, suggests that at room temperature, tetraaquo and pentaaquo-zinc complexes have lower free-energies than hexaaquo-zinc complexes.…”

Section: Introductionmentioning

confidence: 66%

van der Waals Contribution to the Relative Stability of Aqueous Zn(2+) Coordination States

Ducher

Pietrucci

Balan

et al. 2017

J. Chem. Theory Comput.

View full text Add to dashboard Cite

Many properties of aqueous cations depend on their coordination state. However, the lack of long-range order and the dynamic character of aqueous solutions make it difficult to obtain information beyond average coordination parameters. A thorough understanding of the molecular-scale environment of aqueous cations usually requires a combination of experimental and theoretical approaches. In the case of Zn, significant discrepancies occur among theoretical investigations based on first-principles molecular dynamics (FPMD) or free-energy calculations, although experimental data consistently point to a dominant hexaaquo-zinc complex (Zn[HO]) in pure water. In the present study, the aqueous speciation of zinc is theoretically investigated by combining FPMD simulations and free-energy calculations based on metadynamics and umbrella-sampling strategies. The simulations are carried out within the density functional theory (DFT) framework using for the exchange-correlation functional either a standard generalized gradient approximation (GGA) or a nonlocal functional (vdw-DF2) which includes van der Waals interactions. The theoretical environment of Zn is confronted to experiment by comparing calculated and measured X-ray absorption spectra. It is shown that the inclusion of van der Waals interactions is crucial for the correct modeling of zinc aqueous speciation, whereas GGA incorrectly favors tetraaquo- (Zn[HO]) and pentaaquo-zinc (Zn[HO]) complexes, results obtained with the vdW-DF2 functional show that the hexaaquo-zinc complex is more stable than the tetraaquo and pentaaquo-zinc complexes by 13 and by 4 kJ mol, respectively. These results highlight the critical importance of even subtle interactions for the correct balance of different coordination states in aqueous solutions. However, for a given coordination state, GGA leads to a reasonable description of the geometry of the aqueous complex.

show abstract

Section: Introductionmentioning

confidence: 66%

van der Waals Contribution to the Relative Stability of Aqueous Zn(2+) Coordination States

Ducher

Pietrucci

Balan

et al. 2017

J. Chem. Theory Comput.

View full text Add to dashboard Cite

show abstract

“…[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.…”

Section: Discussionmentioning

confidence: 99%

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

Hofer

Hünenberger

2018

The Journal of Chemical Physics

Self Cite

104

View full text Add to dashboard Cite

The absolute intrinsic hydration free energy G • H + ,wat of the proton, the surface electric potential jump χ • wat upon entering bulk water, and the absolute redox potential V • H + ,wat of the reference hydrogen electrode are cornerstone quantities for formulating single-ion thermodynamics on absolute scales. They can be easily calculated from each other but remain fundamentally elusive, i.e., they cannot be determined experimentally without invoking some extra-thermodynamic assumption (ETA). The Born model provides a natural framework to formulate such an assumption (Born ETA), as it automatically factors out the contribution of crossing the water surface from the hydration free energy. However, this model describes the short-range solvation inaccurately and relies on the choice of arbitrary ion-size parameters. In the present study, both shortcomings are alleviated by performing first-principle calculations of the hydration free energies of the sodium (Na + ) and potassium (K + ) ions. The calculations rely on thermodynamic integration based on quantum-mechanical molecular-mechanical (QM/MM) molecular dynamics (MD) simulations involving the ion and 2000 water molecules. The ion and its first hydration shell are described using a correlated ab initio method, namely resolution-of-identity second-order Møller-Plesset perturbation (RIMP2). The next hydration shells are described using the extended simple point charge water model (SPC/E). The hydration free energy is first calculated at the MM level and subsequently increased by a quantization term accounting for the transformation to a QM/MM description. It is also corrected for finite-size, approximate-electrostatics, and potentialsummation errors, as well as standard-state definition. These computationally intensive simulations provide accurate first-principle estimates for G • H + ,wat , χ • wat , and V • H + ,wat , reported with statistical errors based on a confidence interval of 99%. The values obtained from the independent Na + and K + simulations are in excellent agreement. In particular, the difference between the two hydration free energies, which is not an elusive quantity, is 73.9 ± 5.4 kJ mol 1 (K + minus Na + ), to be compared with the experimental value of 71.7 ± 2.8 kJ mol 1 . The calculated values of G • H + ,wat , χ • wat , and V • H + ,wat ( 1096.7 ± 6.1 kJ mol 1 , 0.10 ± 0.10 V, and 4.32 ± 0.06 V, respectively, averaging over the two ions) are also in remarkable agreement with the values recommended by Reif and Hünenberger based on a thorough analysis of the experimental literature ( 1100 ± 5 kJ mol 1 , 0.13 ± 0.10 V, and 4.28 ± 0.13 V, respectively). The QM/MM MD simulations are also shown to provide an accurate description of the hydration structure, dynamics, and energetics. Published by AIP Publishing.

show abstract

“…More recently ab initio methods were used by Pye et al (2006) to study the progressive formation of aquo-chloro zinc complexes. Molecular mechanical methods have also been used to study the solvation structure of zinc (Fatmi et al, 2005(Fatmi et al, , 2006. The structural form of zinc in high ionic strength solutions is of particular interest in modeling the speciation of zinc in industrial processes, such as electrowinning and extractive metallurgy (Wang and Dreisinger, 1998;Guerra and Bestetti, 2006).…”

Section: Introductionmentioning

confidence: 99%

Calculation of equilibrium stable isotope partition function ratios for aqueous zinc complexes and metallic zinc

Black

Kavner

Schauble

2011

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

An extended ab initio QM/MM MD approach to structure and dynamics of Zn(II) in aqueous solution

Cited by 70 publications

References 50 publications

van der Waals Contribution to the Relative Stability of Aqueous Zn(2+) Coordination States

van der Waals Contribution to the Relative Stability of Aqueous Zn(2+) Coordination States

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

Calculation of equilibrium stable isotope partition function ratios for aqueous zinc complexes and metallic zinc

Contact Info

Product

Resources

About