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Subsections

4.1 Plotting selected quantities

The main postprocessing code pp.x extracts the specified data from the data files produced by PWscf (pw.x executable) or CP (cp.x executable); prepares data for plotting by writing them into formats that can be read by several plotting programs.

Quantities that can be read or calculated are:

charge density
spin polarization
various potentials
local density of states at EF
local density of electronic entropy
STM images
selected squared wavefunction
ELF (electron localization function)
RDG (reduced density gradient)
integrated local density of states
Various types of plotting (along a line, on a plane, three-dimensional, polar) and output formats (including the popular cube format) can be specified. Moreover data can be saved to an intermediate (formatted) file so that more data set can be summed or subracted in a later run. The output files can be directly read by the free plotting system Gnuplot (1D or 2D plots), or by code plotrho.x that comes with PostProc and produces PostScript 2D plots, or by advanced plotting software XCrySDen and gOpenMol (3D plots).

See file Doc/INPUT_PP.* for a detailed description of the input for code pp.x. See Example 01 for an example of a charge density plot, Example 03 for an example of STM image simulation.

4.1.0.1 Planar averages

Code plan_avg.x calculates planar averages of Kohn-Sham orbitals. Code average.x calculates planar averages of quantities calculated by pp.x (e.g. potentials, charge, magnetization densities). Note that average.x reads the intermediate file produced by pp.x, not data files produced by pw.x. Examples of usage of average.x can be found in examples/WorcFct_example/ and in examples/dipole_example/.

4.1.0.2 All-electron charge

pawplot.x produces plots of the all-electron charge for PAW calculations.

4.1.0.3 About Bader's analysis

In http://theory.cm.utexas.edu/henkelman/code/bader/ one can find a software that performs Bader's analysis starting from charge on a regular grid. One should use PAW to compute the charge density. The required "cube" format can be produced using pp.x (info by G. Lapenna who has successfully used this technique, but adds: ``Problems occur with polar X-H bonds or in all cases where the zero-flux of density comes too close to atoms described with pseudo-potentials"). This code should perform decomposition into Voronoi polyhedra as well, in place of obsolete code voronoy.x (removed from distribution since v.4.2). Alternatively, you can use CRITIC2, available at https://github.com/aoterodelaroza/critic2, which can read directly pw.x output and ``XSF'' files. CRITIC2 functionaly include Bader's AIM, ELF, laplacian of density and potentials, non-covalente interaction (NCI) plots and much more.


next up previous contents
Next: 4.2 Band structure, Fermi Up: 4 Usage Previous: 4 Usage   Contents
Filippo Spiga 2016-04-24