Thermodynamic anomalies of a network former in a periodic field: Network former in a periodic field.

We study the effect of an external one-dimensional periodic field on thermodynamic anomalies associated with a two-dimensional model liquid with anisotropic interactions. The model system, a 50 : 50 binary mixture of two species of particles interacting with an angle-dependent Lennard-Jones potential, has a rich phase diagram and shows many features of network-forming liquids like water and silica such as a prominent minimum in the pressure-temperature isochore. Confining the system by a commensurate one-dimensional periodic field shifts the temperature of minimum pressure to higher temperatures. A mean-field theory of a lattice-gas in an external field which couples to internal orientational states reproduces these results.