Electrostatic interactions in dissipative particle dynamics using the Ewald sums

Area of Science:

• Computational physics
• Physical chemistry
• Polymer science

Background:

• Standard electrostatic calculations in dissipative particle dynamics (DPD) can lead to artificial ionic pair formation.
• Previous methods, like Groot's lattice-based approach, offer alternatives for simulating electrostatic interactions.

Purpose of the Study:

• To implement and validate the Ewald summation method as an alternative for calculating electrostatic interactions in DPD simulations.
• To investigate the structural properties of bulk electrolytes and polyelectrolyte-surfactant solutions using this method.
• To analyze the influence of charge and solution conditions on polyelectrolyte conformation.

Main Methods:

• Application of the standard Ewald summation method to DPD simulations.
• Inclusion of charge distributions on DPD particles to prevent artificial ionic pairing.
• Analysis of fluid structure using radial distribution functions.
• Calculation of polyelectrolyte radius of gyration under varying pH and salt concentrations.

Main Results:

• The Ewald method accurately reproduces electrostatic interactions in DPD simulations.
• Simulated radial distribution functions for electrolytes and polyelectrolyte-surfactant solutions align with existing literature.
• The radius of gyration of polyelectrolytes increases with net charge, consistent with experimental observations.

Conclusions:

• The Ewald summation method provides a robust and accurate approach for electrostatic interactions in DPD simulations.
• This method is suitable for studying complex systems like electrolytes and charged polymers.
• The findings support the correlation between polymer charge and conformational changes observed experimentally.