Direct methods in structure determination by LEED

Most techniques for determination of surface structure interpret the raw experimental data by trial and error methods. For complex structures this is a very time consuming process because of the exponential growth of possible structures with degrees of freedom. Direct Methods sidestep this difficulty. They have been studied in the context of x-ray diffraction and it is the heavy atom technique of x-ray crystallography that inspires their approach to the surface problem. The idea is that the bulk structure lying behind the surface is known, and a reference surface as near to the true surface structure as possible can be defined. It is subsequently treated as the heavy atom of the surface problem and all phases referred to the reference surface phases. The method works well for some simple examples and future applications of greater sophistication are discussed