  Using a phase field crystal model we study the structure and dynamics of a
drop of colloidal suspension during evaporation of the solvent. We model an
experimental system where contact line pinning of the drop on the substrate is
non-existent. Under such carefully controlled conditions, evaporation of the
drop produces an ordered or disordered arrangement of the colloidal residue
depending on the initial average density of solute and the drying rate. We
obtain a non-equilibrium phase boundary showing amorphous and crystalline
phases of single component and binary mixtures of colloidal particles in the
density- drying rate plane. While single component colloids order in the two
dimensional triangular lattice, a symmetric binary mixture of mutually
repulsive particles orders in a three sub-lattice order where two of the
sub-lattices of the triangular lattice are occupied by the two species of
particles with the third sub-lattice vacant.
