Hello, I?m trying to modify stm.f90 in order to implement Julian Chen?s ?derivative rule? for simulating STM images. For example, if the active orbital of the tip is pz, the contribution of each surface state to the STM signal is proportional to the square of the z-derivative |dpsi/dz|^2, where psi is the surface wavefunction.
Before I get too far, I have two questions about the code: 1) The wavefunction (psic) is stored in a 1-D array. After psic has been transformed to real space, does the index run over a, then b, then c (a,b,c are the lattice vectors)? That is: a1,b1,c1 an,b1,c1; a1,b2,c1 an,b2,c1; a1,bn,c1 an,bn,c1; a1,b1,c2 an,b1,c2; 2) There?s a comment at the beginning of stm.f90, ?It may not properly work if the slab has two symmetric surfaces.? Why would symmetric surfaces present a problem? Thanks, David Pullman Department of Chemistry and Biochemistry San Diego State University San Diego, CA 92182-1030
