Abstract
The question of whether a vapour–liquid phase transition exists in systems of particles with purely dipolar interactions is examined. New Monte Carlo simulation results are presented for the dipolar Yukawa hard sphere (DYHS) fluid with very small values of the attractive Yukawa well depth, almost two orders of magnitude smaller than the characteristic dipolar interaction energy. In this way, it is possible to approach the dipolar hard sphere (DHS) limit. It is found that phase separation is not observable beyond a critical value of the Yukawa energy parameter, even though in thermodynamic and structural terms, the DYHS and DHS systems are very similar. It is suggested that either some very subtle physics distinguishes the DYHS and DHS systems, or the observation of a phase transition in DHSs is precluded by finite-size effects.
Acknowledgements
G.G. was supported by the UK Engineering and Physical Sciences Research Council (Grant No. EP/D002656/1). The financial support of the Natural Science and Engineering Research Council of Canada is gratefully acknowledged. This work has made use of the resources provided by the Edinburgh Compute and Data Facility (ECDF). The ECDF is partially supported by the eDIKT initiative. The research was also enabled by the use of WestGrid computing resources, which were funded in part by the Canada Foundation for Innovation, Alberta Innovation and Science, BC Advanced Education, and the participating research institutions. WestGrid equipment was provided by IBM, Hewlett Packard, and SGI.