Simulation of Ir(III) in Aqueous Solution: The Most Inert Ion Hydrate

2012 ◽  
Vol 65 (12) ◽  
pp. 1582 ◽  
Author(s):  
Philipp A. Pedevilla ◽  
Thomas S. Hofer ◽  
Bernhard R. Randolf ◽  
Bernd M. Rode
Keyword(s):  
Aqueous Solution ◽  
Force Constant ◽  
Hydration Shell ◽  
Hartree Fock ◽  
Hydration Shells ◽  
Hydrate Complex ◽  
Charge Field ◽  
Simulation Time ◽  
Mechanical Charge ◽  
First Hydration Shell

The ab initio quantum mechanical charge field (QMCF) molecular dynamics (MD) approach at Hartree-Fock level was used to simulate the tripositive iridium ion in aqueous solution, evaluating structure and dynamics of its hydrate complex. The Ir-OH2 force constant was of particular interest because of the observed high inertness of Ir(iii) in aqueous solution. Iridium forms three hydration shells. Six water molecules coordinate the ion in the first hydration shell in a well defined octahedral geometry, and no exchanges took place during the simulation time of 15 ps. The second hydration shell is very flexible, however, with a mean residence time of a water molecule of 3.6 ps. The third shell can be identified only by a slight ordering effect. This investigation classified the Ir-OH2 force constant as the strongest ion-OH2 bond known to date.

scholarly journals STRUCTURE OF IRIDIUM(III) HYDRATION BASED ON AB INITIO QUANTUM MECHANICAL CHARGE FIELD MOLECULAR DYNAMICS SIMULATIONS

2010 ◽  
Vol 10 (3) ◽  
pp. 352-356 ◽  
Author(s):  
Ponco Iswanto ◽  
Ria Armunanto ◽  
Harno D. Pranowo
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Complex Structure ◽  
Hydration Shell ◽  
Basis Sets ◽  
Quantum Mechanical ◽  
Ion Hydration ◽  
Charge Field ◽  
Mechanical Charge ◽  
First Hydration Shell

Structural properties of Iridium(III) hydration have been studied based on an ab initio Quantum Mechanical Charge Field (QMCF) Molecular Dynamics (MD) Simulations. The most chemical-relevant region was treated by ab initio calculation at Hartree-Fock level. For the remaining region was calculated by Molecular Mechanics method. LANL2DZ ECP and DZP Dunning basis sets were applied to Ir3+ ion and water, respectively. The average distance of Ir-O in the first hydration shell is 2.03 Å. The QMCF MD Simulation can detect only one complex structure with coordination number of 6 in the first hydration shell. Bond angle analysis shows that Ir3+ ion hydration in the first hydration shell has octahedral structure.

scholarly journals Ab initio QM/MM MD simulations of the hydrated Ca2+ ion

2004 ◽  
Vol 76 (1) ◽  
pp. 37-47 ◽  
Author(s):  
C. F. Schwenk ◽  
B. M. Rode
Keyword(s):  
Density Functional ◽  
Hydration Shell ◽  
Md Simulations ◽  
Distribution Functions ◽  
Quantum Mechanical ◽  
Hartree Fock ◽  
Velocity Autocorrelation ◽  
Exchange Processes ◽  
Hydrate Complex ◽  
Dynamical Properties

The comparison of two different combined quantum mechanical (QM)/molecular mechanical (MM) simulations treating the quantum mechanical region at Hartree-Fock (HF) and B3-LYP density functional theory (DFT) level allowed us to determine structural and dynamical properties of the hydrated calcium ion. The structure is discussed in terms of radial distribution functions, coordination number distributions, and various angular distributions and the dynamical properties, as librations and vibrations, reorientational times and mean residence times were evaluated by means of velocity autocorrelation functions. The QM/MM molecular dynamics (MD) simulation results prove an eightfold-coordinated complex to be the dominant species, yielding average coordination numbers of 7.9 in the HF and 8.0 in the DFT case. Structural and dynamical results show higher rigidity of the hydrate complex using DFT. The high instability of calcium ion's hydration shell allows the observation of water-exchange processes between first and second hydration shell and shows that the mean lifetimes of water molecules in this first shell (<100 ps) have been strongly overestimated by conclusions from experimental data.

A Comparative Quantum Mechanical Charge Field Study of Uranyl Mono- and Dicarbonate Species in Aqueous Solution

2013 ◽  
Vol 117 (50) ◽  
pp. 16174-16187 ◽  
Author(s):  
Andreas O. Tirler ◽  
Alexander K. H. Weiss ◽  
Thomas S. Hofer
Keyword(s):  
Aqueous Solution ◽  
Field Study ◽  
Quantum Mechanical ◽  
Charge Field ◽  
Mechanical Charge

Guanidinium in aqueous solution studied by quantum mechanical charge field-molecular dynamics (QMCF-MD)

2012 ◽  
Vol 14 (19) ◽  
pp. 7012 ◽  
Author(s):  
Alexander K. H. Weiss ◽  
Thomas S. Hofer ◽  
Bernhard R. Randolf ◽  
Bernd M. Rode
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Quantum Mechanical ◽  
Charge Field ◽  
Mechanical Charge

scholarly journals Pemodelan Interaksi Serium(III) dan Air dengan Teori Perhitungan Ab Initio serta Penentuan Himpunan Fungsi Basisnya

2012 ◽  
Vol 2 (4) ◽  
Author(s):  
Eva Vaulina Yulistia Delsy ◽  
Tien Setyaningtyas ◽  
Ponco Iswanto ◽  
Nunik Fitri Utami
Keyword(s):  
Ab Initio ◽  
Water Cluster ◽  
Quantum Mechanical ◽  
Hartree Fock ◽  
Lennard Jones ◽  
Charge Field ◽  
Mechanical Charge

Penentuan himpunan fungsi basis (HFB) untuk simulasi ion Ce3+dalam air telah dilakukan dalampenelitian ini. Penentuan HFB harus dilakukan karena HFB yang tersedia adalah HFB untuk unsurCe(III), sedangkan model sistem kimia yang dikaji dalam penelitian ini adalah Ce dalam bentuk ion(Ce3+). Penentuan HFB dimulai dengan menerapkan semua HFB Ce yang diusulkan dari web basisset. Pemilihan HFB dilakukan dengan menggunakan dua metode. Pertama, mencocokkan kurvaenergi interaksi terhadap jarak dengan kurva potensial interaksi dua partikel Lennard-Jones 6-12(metode scan 2 body). Ke dua, optimasi struktur kompleks [Ce(H2O)n]3+ kemudian dibandingkandengan data eksperimen (metode water cluster). Tidak ada transfer muatan yang terjadi padainteraksi Ce3+ dengan air. HFB H dan O ditetapkan menggunakan DZP Dunning. Jenis simulasiDinamika Molekuler yang direkomendasikan untuk mengkaji ion Ce3+ di dalam air adalah MK/MMdengan menggunakan HFB Stutgard RSC ANO/ECP dan Quantum Mechanical Charge Field(QMCF) dengan menggunakan HFB SBKJC VDZ ECP pada tingkat teori Hartree-Fock (HF).

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