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Accounting for electronic polarization in non-polarizable force fields
Igor Leontyev1, Alexei Stuchebrukhov
1Department of Chemistry, University of California Davis, One Shields Avenue, Davis, California 95616, USA.
Physical Chemistry Chemical Physics : PCCP
|January 8, 2011
Summary
Electronic polarizability in molecular dynamics simulations requires scaling ion charges by 0.7. This addresses solvation energy and improves protein dynamics, explaining effective water dipole values in simulations.
Area of Science:
- Computational Chemistry
- Molecular Dynamics Simulations
- Biophysics
Background:
- Conventional non-polarizable force fields often use unscaled charges for ions and ionized groups.
- Neglecting electronic solvation energy in simulations can lead to inaccuracies in ion-ion pair interactions.
- Existing models struggle to explain the discrepancy between theoretical and effective water dipole moments.
Purpose of the Study:
- To discuss the role of electronic polarizability in molecular dynamics simulations.
- To propose a model for scaling charges in non-polarizable force fields.
- To explain the effective dipole moment of water in empirical potentials.
Main Methods:
- Developing a theoretical model for electronic polarizability.
- Analyzing solvation energy and ion-ion pair interactions.
- Comparing simulation results with and without electronic screening.
Main Results:
- A charge scaling factor of approximately 0.7 is proposed for ionized groups and ions.
- The model explains how neglecting electronic solvation can yield correct results for total solvation energy but not ion interactions.
- Inclusion of electronic screening significantly alters protein dynamics and yields novel results.
- The effective dipole of water is explained by its electronic dielectric constant: μ(eff) = μ/√ε(el).
Conclusions:
- Scaling charges in non-polarizable force fields is crucial for accurate molecular dynamics simulations.
- The proposed framework provides insights into effective parameters for simulating water in various environments.
- Accurate modeling of electronic polarizability is essential for understanding protein dynamics and solute interactions.
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