The phase diagram of water from quantum simulations

7 pags, 6 figs, 1 tabThe phase diagram of water has been calculated from the TIP4PQ/2005 model, an empirical rigid non-polarisable model. The path integral Monte Carlo technique was used, permitting the incorporation of nuclear quantum effects. The coexistence lines were traced out using the Gibbs-Duhem integration method, once having calculated the free energies of the liquid and solid phases in the quantum limit, which were obtained via thermodynamic integration from the classical value by scaling the mass of the water molecule. The resulting phase diagram is qualitatively correct, being displaced to lower temperatures by 15-20 K. It is found that the influence of nuclear quantum effects is correlated to the tetrahedral order parameter. © 2012 The Owner Societies.This work was funded by grants FIS2010-16159 and FIS2010-15502 of the Dirección General de Investigación and S2009/ESP-1691-QF-UCM (MODELICO) of the Comunidad Autónoma de Madrid