Multiple "time step" Monte Carlo simulations: application to charged systems with Ewald summation

Area of Science:

• Computational Chemistry
• Statistical Mechanics
• Molecular Dynamics

Background:

• Monte Carlo (MC) simulations are crucial for studying molecular systems.
• Efficient simulation schemes are needed to reduce computational cost.
• The Ewald summation is commonly used for calculating long-range interactions in periodic systems.

Purpose of the Study:

• To compare the efficiency of the multiple time step Monte Carlo (MTS-MC) method with the standard Metropolis Monte Carlo (MC) method.
• To evaluate the structural and thermodynamic properties of the simple point charge water model using both simulation techniques.
• To assess the performance of MTS-MC with a real-/reciprocal-space split of the Ewald summation.

Main Methods:

• Implementation of the multiple time step Monte Carlo (MTS-MC) method.
• Application of the simple point charge (SPC) water model.
• Utilizing the Ewald summation technique for electrostatic interactions.
• Comparison with the standard Metropolis Monte Carlo (MC) method.

Main Results:

• MTS-MC achieved speedups of 4.5-7.5 times compared to MC for systems of 108-500 water molecules.
• Observable properties were calculated as a function of CPU time for both methods.
• Correlation functions indicated the efficiency gains of the MTS-MC approach.
• The real-/reciprocal-space split in MTS-MC demonstrated improved computational performance.

Conclusions:

• The MTS-MC method provides a significant acceleration for molecular simulations of water models.
• The proposed MTS-MC scheme is an efficient alternative to standard MC methods for calculating structural and thermodynamic properties.
• This approach is particularly effective when combined with Ewald summation for handling long-range interactions.