Field-theoretic simulations beyond δ-interactions: Overcoming the inverse potential problem in auxiliary field...

Area of Science:

• Computational physics and chemistry
• Soft matter physics
• Polymer science

Background:

• Field-theoretic simulations (FTS) are limited by the inverse potential (u^-1) in model equations.
• Current FTS methods restrict applications to simple pairwise interactions, like delta-function potentials for excluded volume effects.

Purpose of the Study:

• To overcome limitations of current field-theoretic simulations by enabling the use of more complex pair interaction functions.
• To develop and validate an alternative approach for handling inverse potentials in FTS.

Main Methods:

• Reviewed and classified existing nonbonded pair interactions in field-theoretic models.
• Developed an alternative approach using a saddle-point approximation to address the inverse potential problem.
• Utilized the Morse potential as a test case, calibrating the inverse potential (u^-1) with molecular dynamics simulations.

Main Results:

• The proposed saddle-point approximation method allows for a broader range of pair interaction functions in FTS.
• The calibrated inverse potential (u^-1) derived from the Morse potential is consistent with field-theoretic model equations.
• Self-consistent field simulations using the new approach accurately reproduce fluid structure from initial random states.

Conclusions:

• The novel approach expands the applicability of field-theoretic simulations to systems with complex interatomic potentials.
• This method enhances the accuracy and scope of simulations for complex fluids and polymers.
• The successful application with the Morse potential demonstrates the robustness of the technique.