[Pw_forum] STS spectra

[Daniele Passerone]

Dear Pwscf users and developers, 

The postprocessing facilities of espresso allow to extract stm images,
that correspond in Tersoff-Hamann approximation to the 
localized density of states integrated between Efermi and a given
(positive or negative) bias. The more convenient way to analyze this 
quantity is in my opinion by generating a 3d grid and visualizing it
with xcrysden, which incidentally can also show planes parallel to the
cell 
sides.

The ILDOS option of pp.x (plot_num=10) somewhat extends this, allowing
to compute the LDOS integrated between emin and emax. 
STS (scanning tunneling spectroscopy) experiments sample the local
density of states at a surface: one obtains a profile of dI/dV 
at a certain point on the surface, and this gives valuable information
about the local conductivity and presence of peaks in the DOS etc.

The question is: what is the more convenient and fast way to get the
LDOS profile from Emin to Emax,  on a certain plane (let us say, 2
Angstrom above the surface)? I thought one could make several jobs of
pp.x : from Emin to Emin+DeltaE, from Emin + Delta E to 
Emin + 2*Delta E.... and so on... but maybe there are much better ways
to do that.

Thank you in advance for any advice,
Daniele




*************************************************************

Dr. Daniele Passerone
Abteilung nanotech at surfaces
Theory and atomistic simulation of materials
Empa - Materials Science & Technology
Ueberlandstrasse 129
CH-8600 Dübendorf

Tel +41 44 823 4877
Fax +41 44 823 4031

daniele.passerone at empa.ch 
www.empa.ch 
E-mail from non-academic servers:
daniele at passerone.net

************************************************************