Rational Design of Particle Mesh Ewald Compatible Lennard-Jones Parameters for +2 Metal Cations in Explicit Solvent
Pengfei Li1, Benjamin P Roberts, Dhruva K Chakravorty
12328 New Physics Building, PO Box 118435, University of Florida, Gainesville, Florida 32611-8435, .
Journal of Chemical Theory and Computation
|August 6, 2013
Summary
New Lennard-Jones parameters were developed for metal ions in molecular dynamics (MD) simulations. These improved parameters enhance accuracy for metal (M(II)) cations in Particle Mesh Ewald (PME) simulations with common water models.
Area of Science:
- Computational chemistry
- Biophysics
- Materials science
Background:
- Metal ions are crucial in biological systems, necessitating accurate molecular dynamics (MD) simulations.
- Current nonbonded models (Lennard-Jones + electrostatics) for metal ions in MD simulations have limited parameter transferability.
- Particle Mesh Ewald (PME) simulations are increasingly popular for their speed and accuracy in handling long-range electrostatics.
Purpose of the Study:
- To systematically design and validate Lennard-Jones (LJ) parameters for 24 +2 metal (M(II)) cations for use in PME-based MD simulations.
- To improve the accuracy and transferability of metal ion parameters across different water models.
- To provide optimized parameters that balance reproducing experimental hydration properties.
Main Methods:
- Systematic design of LJ parameters for M(II) cations using the thermodynamic integration (TI) method.
- Periodic boundary MD simulations employing PME for long-range electrostatics.
- Evaluation of hydration free energies (HFEs), ion-oxygen distance (IOD), and coordination numbers (CNs) for various LJ parameter combinations and four water models (TIP3P, SPC/E, TIP4P, TIP4PEW).
Main Results:
- Existing M(II) ion LJ parameters showed limited transferability, necessitating new parameters for PME simulations.
- Hydration free energies, ion-oxygen distances, and coordination numbers were found to be highly correlated.
- M(II) ions with identical parameters exhibited different HFEs but similar structural properties across different water models, indicating model-specific parameterization is needed.
- A curve fitting approach using noble gas experimental data guided the generation of compromise LJ parameters.
- Three sets of LJ parameters were developed for M(II) cations, optimized for TIP3P, SPC/E, and TIP4PEW water models, achieving a balance in reproducing experimental data with an estimated uncertainty of ±1 kcal/mol in HFEs.
Conclusions:
- The developed LJ parameters represent a significant improvement for simulating M(II) cations in MD using common water models and PME.
- The study highlights the challenges in simultaneously reproducing diverse experimental values with simple nonbonded models, often underestimating short-range ion-water interactions.
- Future advancements may require more sophisticated non-bonded models, potentially including polarization effects, for even higher accuracy.
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