Multiscale molecular dynamics using the matched interface and boundary method

Area of Science:

• Computational chemistry
• Biophysics
• Molecular modeling

Background:

• The Poisson-Boltzmann (PB) equation is crucial for electrostatic analysis in biological systems.
• Current PB-based molecular dynamics (MD) methods face challenges with accuracy, stability, and complex interfaces.
• Singularities in geometry and charge further complicate numerical solutions.

Purpose of the Study:

• To develop a more accurate and stable PB-based MD approach for biomolecular simulations.
• To address limitations in handling complex solvent-solute interfaces and singularities.
• To enable reliable electrostatic force calculations in large biological systems.

Main Methods:

• Utilized the matched interface and boundary (MIB) method for a second-order accurate PB solver.
• Derived a new formulation for electrostatic forces compatible with sharp molecular surfaces.
• Employed Cartesian-grid surface integration for dielectric boundary force evaluation.
• Integrated the MIB-based PB solver with the AMBER package for MD simulations.

Main Results:

• Achieved numerically stable solutions for PB equations with discontinuous dielectric coefficients and singularities.
• Developed accurate reaction field forces through direct differentiation of electrostatic potential.
• Successfully assigned electrostatic forces at reentrant surfaces to relevant atoms.
• Validated the accuracy and stability of the electrostatic force calculations through extensive numerical tests.

Conclusions:

• The MIB method significantly improves the stability and accuracy of PB-based MD simulations.
• This new approach overcomes key obstacles in applying PB-based MD to complex biomolecular systems.
• The implemented method provides a reliable tool for simulating large biological systems with enhanced electrostatic analysis.