Absence of simulation evidence for critical depletion in slit-pores

TL;DR

This paper shows that previously reported critical depletion in slit-pore fluids is a simulation artifact caused by potential truncation errors, emphasizing the need for careful correction methods.

Contribution

It identifies the source of the apparent critical depletion as a systematic error from long-range correction approximations in simulations.

Findings

The observed depletion is an artifact, not a physical phenomenon.

Long-range correction errors significantly affect local density near critical points.

Recommendations are provided to avoid such errors in future simulations.

Abstract

Recent Monte Carlo simulation studies of a Lennard-Jones fluid confined to a mesoscopic slit-pore have reported evidence for ``critical depletion'' in the pore local number density near the liquid-vapour critical point. In this note we demonstrate that the observed depletion effect is in fact a simulation artifact arising from small systematic errors associated with the use of long range corrections for the potential truncation. Owing to the large near-critical compressibility, these errors lead to significant changes in the pore local number density. We suggest ways of avoiding similar problems in future studies of confined fluids.