  We investigate the structural and thermodynamic properties of a new class of
patchy colloids, referred to as inverse patchy colloids (IPCs) in their fluid
phase via both theoretical methods and simulations. IPCs are nano- or micro-
meter sized particles with differently charged surface regions. We extend
conventional integral equation schemes to this particular class of systems: our
approach is based on the so-called multi-density Ornstein-Zernike equation,
supplemented by the associative Percus-Yevick approximation (APY). To validate
the accuracy of our framework, we compare the obtained results with data
extracted from $NpT$ and $NVT$ Monte Carlo simulations. In addition, other
theoretical approaches are used to calculate the properties of the system: the
reference hypernetted-chain (RHNC) method and the Barker-Henderson
thermodynamic perturbation theory. Both APY and RHNC frameworks provide
accurate predictions for the pair distribution functions: APY results are in
slightly better agreement with MC data, in particular at lower temperatures
where the RHNC solution does not converge.
