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Title: Effects of confinement on anomalies and phase transitions of core-softened fluids

We use molecular dynamics simulations to study how the confinement affects the dynamic, thermodynamic, and structural properties of a confined anomalous fluid. The fluid is modeled using an effective pair potential derived from the ST4 atomistic model for water. This system exhibits density, structural, and dynamical anomalies, and the vapor-liquid and liquid-liquid critical points similar to the quantities observed in bulk water. The confinement is modeled both by smooth and structured walls. The temperatures of extreme density and diffusion for the confined fluid show a shift to lower values while the pressures move to higher amounts for both smooth and structured confinements. In the case of smooth walls, the critical points and the limit between fluid and amorphous phases show a non-monotonic change in the temperatures and pressures when the nanopore size is increase. In the case of structured walls, the pressures and temperatures of the critical points varies monotonically with the pore size. Our results are explained on basis of the competition between the different length scales of the fluid and the wall-fluid interaction.
Authors:
;  [1] ;  [2] ;  [3]
  1. Instituto de Física, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, CEP 91501-970, Porto Alegre, RS (Brazil)
  2. Campus Caçapava do Sul, Universidade Federal do Pampa, Av. Pedro Anunciação, s/n, CEP 96570-000, Caçapava do Sul, RS (Brazil)
  3. Campus Cerro Largo, Universidade Federal da Fronteira Sul, Av. Jacob Reinaldo Haupenthal, 1580. CEP 97900-000, Cerro Largo, RS (Brazil)
Publication Date:
OSTI Identifier:
22415615
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 13; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; AMORPHOUS STATE; COMPUTERIZED SIMULATION; DENSITY; DIFFUSION; LIQUIDS; MOLECULAR DYNAMICS METHOD; PHASE TRANSFORMATIONS; POTENTIALS; VAPORS; WATER