Crystal structure of dichlorofluoromethane

The crystal structure of dichlorofluoromethane or freon 21 (CHFCl₂) has been determined at temperatures ranging from 5 K to 105 K using neutron powder profile techniques. There is only one phase present at all temperatures, with eight molecules per unit cell positioned on general sites in the space group Pbca. Starting positions and orientations of the molecules were determined to high accuracy using an energy minimization process with atom-atom potentials. Coulombic interactions, as represented using atomic charges, were shown to be unimportant in determining the structure.