Hi Yeti, Thanks a lot for your email. The ordinate is LDOS. I intend to simulate STM from density functional Kohn-Sham eigenfunctions. As I mentioned I have LDOS values on a N1xN2xN3 grid. This kind for data format is the most usual among first-principles DFT codes (VASP, SIESTA, WIEN2k, GAUSSIAN, etc). Usually there are two ways to simulate an STM image, assuming that the tunneling current is proportional to the LDOS at the tip location. The two ways are (i) constant heigh or (ii) constant current. In constant heigh mode we simply have to produce a slice of LDOS at a specified z-value and plot LDOS(x,y). However, real STM usually records the height of the tip (z-coordinate) by scanning over a constant current isosurface over the sample. So, we need to plot z(x,y) (this is now a 2D image) so that DLOS(x,y,z)=Const. Thanks a lot, /J
On 09 May 2014, at 21:58, David Nečas (Yeti) <[email protected]> wrote: > On Fri, May 09, 2014 at 08:27:53PM +0000, José Coutinho wrote: >> Not sure if you understood it right. I meant the maximum z-coordinate >> that corresponds to a user-defined (constant) LDOS(E+dE,x,y,z). >> Basically, in STM the tip hoovers over a landscape with approximately >> constant LDOS. > > I admit that, being the kind of physicist preferring pencil and paper to > fickle real-world samples, I have only some basic understanding of STM. > Anyway, for me the full STM description would have 4 abscissa axes (the > fourth being voltage, electron energy, or something similar), whether we > talk about current, density of states, or anything. So please dumb it > down for me by saying explicitly what are the axes for the N1×N2×N3 grid > and what is the value (ordinate) because I am still missing one axis > somewhere. > > Thanks, > > Yeti > > > ------------------------------------------------------------------------------ > Is your legacy SCM system holding you back? Join Perforce May 7 to find out: > • 3 signs your SCM is hindering your productivity > • Requirements for releasing software faster > • Expert tips and advice for migrating your SCM now > http://p.sf.net/sfu/perforce > _______________________________________________ > Gwyddion-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/gwyddion-users ------------------------------------------------------------------------------ Is your legacy SCM system holding you back? Join Perforce May 7 to find out: • 3 signs your SCM is hindering your productivity • Requirements for releasing software faster • Expert tips and advice for migrating your SCM now http://p.sf.net/sfu/perforce _______________________________________________ Gwyddion-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/gwyddion-users
