A simple method for introducing a cutoff to hydrodynamic interactions in Brownian dynamics simulations.

Area of Science:

• Computational physics
• Biophysics
• Molecular dynamics

Background:

• Brownian dynamics (BD) simulations with hydrodynamic interactions (HIs) are crucial for modeling macromolecular diffusion.
• The Rotne-Prager-Yamakawa (RPY) model accurately captures these interactions but is computationally expensive.
• Implementing distance cutoffs to reduce computational cost often results in non-positive definite diffusion tensors, hindering simulations.

Purpose of the Study:

• To develop a computationally efficient method for including hydrodynamic interactions in BD simulations.
• To ensure the diffusion tensor remains positive definite when applying distance cutoffs.
• To enable seamless integration of HI effects at varying levels of detail.

Main Methods:

• A distance-based scaling approach was applied to the RPY hydrodynamic interaction terms.
• This method modifies the RPY tensor to maintain positive definiteness when a cutoff is introduced.
• The Ermak-McCammon BD-HI algorithm was adapted to utilize the modified diffusion tensor.

Main Results:

• A novel, simple distance-based scaling scheme was successfully implemented.
• The proposed method guarantees a positive definite diffusion tensor, even with distance cutoffs.
• This approach allows for a smooth transition between simulations with and without hydrodynamic interactions.

Conclusions:

• The developed method offers an efficient and robust way to incorporate hydrodynamic interactions in BD simulations.
• It overcomes the computational expense and mathematical instability issues associated with distance cutoffs.
• This technique enhances the applicability of BD simulations for studying macromolecular dynamics.