Real space electrostatics for multipoles. II. Comparisons with the Ewald sum

Area of Science:

• Computational chemistry and physics
• Materials science
• Molecular modeling

Background:

• Accurate calculation of electrostatic interactions is crucial for molecular simulations.
• Traditional methods like Ewald summation are computationally intensive, especially for large systems.
• Real-space methods offer a computationally efficient alternative for electrostatic calculations.

Purpose of the Study:

• To test and compare the performance of shifted potential (SP), gradient shifted force (GSF), and Taylor shifted force (TSF) real-space methods.
• To evaluate these methods against the established multipolar Ewald sum for multipole interactions.
• To assess their suitability for condensed-phase environments up to quadrupole-quadrupole interactions.

Main Methods:

• Comparison of energy differences, molecular forces, and torques between real-space methods and Ewald summation.
• Investigation of energy conservation, structural, and dynamical properties using molecular dynamics simulations.
• Testing across various condensed-phase environments.

Main Results:

• The shifted potential (SP) method demonstrated excellent agreement for configurational energy differences, forces, and torques, suitable for Monte Carlo simulations.
• The gradient shifted force (GSF) method showed the best agreement with Ewald-derived energies, forces, and torques among the shifted-force methods.
• Both SP and GSF methods accurately reproduced structural and dynamical properties in liquid models, with GSF exhibiting superior energy conservation for molecular dynamics.

Conclusions:

• The GSF method is an excellent choice for efficient computation of electrostatic interactions in molecular dynamics simulations due to its accuracy and energy conservation.
• The SP method is well-suited for Monte Carlo simulations.
• These real-space methods provide accurate and efficient alternatives to Ewald summation for simulating multipole interactions in condensed phases.