### Abstract

Structural transitions are examined in quasi-one-dimensional systems of freely rotating hard squares, which are confined between two parallel walls. We find two competing phases: one is a fluid where the squares have two sides parallel to the walls, while the second one is a solidlike structure with a zigzag arrangement of the squares. Using transfer matrix method we show that the configuration space consists of subspaces of fluidlike and solidlike phases, which are connected with low probability microstates of mixed structures. The existence of these connecting states makes the thermodynamic quantities continuous and precludes the possibility of a true phase transition. However, thermodynamic functions indicate strong tendency for the phase transition and our replica exchange Monte Carlo simulation study detects several important markers of the first order phase transition. The distinction of a phase transition from a structural change is practically impossible with simulations and experiments in such systems like the confined hard squares.

Original language | English |
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Article number | 050603 |

Journal | Physical Review E - Statistical, Nonlinear, and Soft Matter Physics |

Volume | 94 |

Issue number | 5 |

DOIs | |

Publication status | Published - Nov 28 2016 |

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### ASJC Scopus subject areas

- Statistical and Nonlinear Physics
- Statistics and Probability
- Condensed Matter Physics

### Cite this

*Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*,

*94*(5), [050603]. https://doi.org/10.1103/PhysRevE.94.050603

**Anomalous structural transition of confined hard squares.** / Gurin, Péter; Varga, S.; Odriozola, Gerardo.

Research output: Contribution to journal › Article

*Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*, vol. 94, no. 5, 050603. https://doi.org/10.1103/PhysRevE.94.050603

}

TY - JOUR

T1 - Anomalous structural transition of confined hard squares

AU - Gurin, Péter

AU - Varga, S.

AU - Odriozola, Gerardo

PY - 2016/11/28

Y1 - 2016/11/28

N2 - Structural transitions are examined in quasi-one-dimensional systems of freely rotating hard squares, which are confined between two parallel walls. We find two competing phases: one is a fluid where the squares have two sides parallel to the walls, while the second one is a solidlike structure with a zigzag arrangement of the squares. Using transfer matrix method we show that the configuration space consists of subspaces of fluidlike and solidlike phases, which are connected with low probability microstates of mixed structures. The existence of these connecting states makes the thermodynamic quantities continuous and precludes the possibility of a true phase transition. However, thermodynamic functions indicate strong tendency for the phase transition and our replica exchange Monte Carlo simulation study detects several important markers of the first order phase transition. The distinction of a phase transition from a structural change is practically impossible with simulations and experiments in such systems like the confined hard squares.

AB - Structural transitions are examined in quasi-one-dimensional systems of freely rotating hard squares, which are confined between two parallel walls. We find two competing phases: one is a fluid where the squares have two sides parallel to the walls, while the second one is a solidlike structure with a zigzag arrangement of the squares. Using transfer matrix method we show that the configuration space consists of subspaces of fluidlike and solidlike phases, which are connected with low probability microstates of mixed structures. The existence of these connecting states makes the thermodynamic quantities continuous and precludes the possibility of a true phase transition. However, thermodynamic functions indicate strong tendency for the phase transition and our replica exchange Monte Carlo simulation study detects several important markers of the first order phase transition. The distinction of a phase transition from a structural change is practically impossible with simulations and experiments in such systems like the confined hard squares.

UR - http://www.scopus.com/inward/record.url?scp=84999636143&partnerID=8YFLogxK

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U2 - 10.1103/PhysRevE.94.050603

DO - 10.1103/PhysRevE.94.050603

M3 - Article

AN - SCOPUS:84999636143

VL - 94

JO - Physical review. E

JF - Physical review. E

SN - 2470-0045

IS - 5

M1 - 050603

ER -