Liquid polymorphism, order-disorder transitions and anomalous behavior : a Monte Carlo study of the Bell-Lavis model for water

• Autor(a) principal: Fiore, Carlos Eduardo
• Data de Publicação: 2009
• Outros Autores: Szortyka, Marcia Martins, Barbosa, Marcia Cristina Bernardes, Henriques, Vera Bohomoletz
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/205428
• topic: Física da matéria condensada; Diagramas de fase; Estrutura líqüida; Transformações líquido-líquido; Transformacoes de ordem-desordem; Gás de rede; Método de Monte Carlo; Modelo de ising

The Bell–Lavis model for liquid water is investigated through numerical simulations. The lattice-gas model on a triangular lattice presents orientational states and is known to present a highly bonded low density phase and a loosely bonded high density phase. We show that the model liquid-liquid transition is continuous, in contradiction with mean-field results on the Husimi cactus and from the cluster variational method. We define an order parameter which allows interpretation of the transition as an order-disorder transition of the bond network. Our results indicate that the order-disorder transition is in the Ising universality class. Previous proposal of an Ehrenfest second order transition is discarded. A detailed investigation of anomalous properties has also been undertaken. The line of density maxima in the HDL phase is stabilized by fluctuations, absent in the mean-field solution.