2013/09/05 by Danh-Tai Hoang, Hoang, Danh-Tai, H. T. Diep +2
Materials Science · Physics and Astronomy · #FOS: Physical sciences #Liquid Crystal Research Advancements #Material Dynamics and Properties #Statistical Mechanics (cond-mat.stat-mech) #Theoretical and Computational Physics #cond-mat.stat-mech
paper · pdf · doi:10.48550/arxiv.1309.1427
arxiv created 2013/09/05 · openalex publication_date 2013/09/05 · arxiv updated 2013/09/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We study the phase transition in a system composed of dimers interacting with each other via a nearest-neighbor (NN) exchange J and competing interactions taken from a truncated dipolar coupling. Each dimer occupies a link between two nearest sites of a simple cubic lattice. We suppose that dimers are self-avoiding and can have only three orientations which coincide with the x, y or z direction. The interaction J is attractive if the two dimers are parallel with each other at the NN distance, zero otherwise. The truncated dipolar interaction is characterized by two parameters: its amplitude D and the cutoff distance rc. Using the steepest-descent method, we determine the ground-state (GS) configuration as functions of D and rc. We then use Monte Carlo simulations to investigate the nature of the low-temperature phase and to determine characteristics of the phase transition from the ordered phase to the disordered phase at high temperatures at a given dimer concentration. We show that as the temperature increases, dimers remain in the compact state and the transition from the low-T compact phase to the disordered phase where dimers occupy the whole space is of second order when D is small, but it becomes of first order for large enough D, for both polarized and non polarized dimers. This transition has a resemblance with the unfolding polymer transition. The effect of rc is discussed.