Electrospray molecular dynamics simulations using an octree-based Coulomb interaction method.

Area of Science:

• Computational Chemistry
• Materials Science
• Physical Chemistry

Background:

• Electrospray of ionic liquids (ILs) is crucial for various applications.
• Accurate modeling of Coulomb interactions is essential for simulating IL electrospray.
• Existing models can be computationally expensive or lack specific predictive capabilities.

Purpose of the Study:

• To develop and validate a novel octree-based Coulomb interaction model for IL electrospray.
• To compare the performance and results of the octree-based model against established methods.
• To investigate the influence of the model on Taylor cone formation and ion emission characteristics.

Main Methods:

• Implementation of an octree-based method to categorize Coulomb interactions (intra- and interleaf).
• Classification criterion based on the Bjerrum length of the ionic liquid.
• Molecular dynamics simulations comparing the octree method with direct Coulomb and damped shifted force (DSF) methods.

Main Results:

• The octree-based model accurately reproduces Coulomb energy, matching established methods without an external electric field.
• Distinct differences in simulation outcomes were observed with an external electric field compared to the direct Coulomb method.
• The octree method demonstrated faster Taylor cone formation and predicted the emission of larger ion species (dimers, trimers) and a smaller emission cone.

Conclusions:

• The octree-based Coulomb interaction model offers a computationally efficient and accurate approach for simulating ionic liquid electrospray.
• The model provides unique insights into Taylor cone dynamics and ion emission phenomena.
• This novel method enhances the simulation of complex IL electrospray processes in molecular dynamics.