Control of phase ordering and elastic properties in phase field crystals through three-point direct correlation

TL;DR

This paper investigates how three-point direct correlation influences phase stability, elastic properties, and phase coexistence in phase field crystal models, enabling enhanced control over material behaviors in simulations.

Contribution

It introduces a novel approach incorporating three-point correlation into PFC models, significantly affecting phase diagrams, elastic constants, and coexistence phenomena.

Findings

Three-point correlation shifts the critical point of order-disorder transition.

Control over elastic constants range is achieved through three-point correlation.

The method models solid and soft matter systems with diverse phase coexistences.

Abstract

Effects of three-point direct correlation on properties of the phase field crystal (PFC) modeling are examined, for the control of various ordered and disordered phases and their coexistence in both three-dimensional and two-dimensional systems. Such effects are manifested via the corresponding gradient nonlinearity in the PFC free energy functional that is derived from classical density functional theory. Their significant impacts on the stability regimes of ordered phases, phase diagrams, and elastic properties of the system, as compared to those of the original PFC model, are revealed through systematic analyses and simulations. The nontrivial contribution from three-point direct correlation leads to the variation of the critical point of order-disorder transition to which all the phase boundaries in the temperature-density phase diagram converge. It also enables the variation and control of system elastic constants over a substantial range as needed in modeling different types of materials with the same crystalline structure but different elastic properties. The capability of this PFC approach in modeling both solid and soft matter systems is further demonstrated through the effect of three-point correlation on controlling the vapor-liquid-solid coexistence and transitions for body-centered cubic (bcc) phase and on achieving the liquid-stripe or liquid-lamellar phase coexistence. All these provide a valuable and efficient method for the study of structural ordering and evolution in various types of material systems.