# Density- and Temperature-Dependent Potentials: Redefinition of the Local Density to Improve the Simulation of Liquids within Generalized Dissipative Particle Dynamics

## TL;DR

This paper improves the simulation of liquid systems by redefining how local density is calculated in a physics-based modeling method.

## Contribution

A new local density definition is introduced to enhance the accuracy of liquid simulations in GenDPDE.

## Key findings

- The traditional local density estimator in DPD causes unphysical particle clustering in liquid simulations.
- The new local density definition enables physically meaningful results for liquid argon and water simulations.
- The revised method allows GenDPDE to effectively model complex fluid systems in various scenarios.

## Abstract

In this work, we
apply the mesoscopic Generalized Energy-Conserving
Dissipative Particle Dynamics (GenDPDE) method (J. Bonet Avalos et
al., Phys. Chem. Chem. Phys.
2019, 21,
24891) to analyze liquid phases. We demonstrate that the traditional
DPD estimator of the particle local density is inadequate for the
simulation of liquid phase conditions, as it leads to an unphysical
behavior, typically in the form of particle clustering, that modifies
the local structure and prevents the system from equilibrating at
the sought thermodynamic state point. We therefore propose an alternative
definition for the local density calculation which significantly improves
its estimation and crucially allows us to recover physically meaningful
results. We prove the beneficial effects of this redefinition by analyzing
the thermodynamic properties and local structure of liquid argon and
water, drawing a comparison between the outcome of equilibrium simulations
considering the two density estimators. With the introduction of the
new local density expression, GenDPDE is suitable for the qualitative
and quantitative analysis of complex fluid systems in a variety of
relevant scenarios, including liquid phases.