Self-assembly and growth of manganese phthalocyanine (MnPc) molecules on an Au(111) surface is investigated by means of low-temperature scanning tunneling microscopy.At the initial stage,MnPc molecules preferentially occupy the step edges and elbow sites on the Au(111) surface,then they are separately adsorbed on the face-centered cubic and hexagonal closely packed regions due to a long-range repulsive molecule-molecule interaction.After the formation of a closely packed monolayer,molecular islands with second and third layers are observed. Self-assembly and growth of manganese phthalocyanine (MnPc) molecules on an Au (111) surface is investigated by means of low-temperature scanning tunneling microscopy. At the initial stage, MnPc molecules preferentially occupy the step edges and elbow sites on the Au 111) surface, then they are separately adsorbed on the face-centered cubic and hexagonal closely packed regions due to a long-range repulsive molecule-molecule interaction. After the formation of a closely packed monolayer, molecular islands with second and third layers are observed .