1.29 How do I specify a custom path for plotting the electronic bands and phonon dispersions?

You have to give an explicit path after the INPUT_THERMO namelist (see what='scf_bands' and what='scf_2d_bands'). There are two possibilities to specify a path in the Brillouin zone. You can use explicit coordinates of the first and last points of each line (in cartesian or crystal coordinates) and a weight that indicates the number of points in the line, or you can use labels to indicate the first and/or the last points. The available labels depend on the Brillouin zone and are illustrated in the file Doc/brillouin_zones.pdf in the main QE documentation. Labels for points given by explicit coordinates can be added after the weights. Usually, the same label that indicates the coordinates of the point is written in the dispersion plot, but it is also possible to override this label, adding a letter after the weight as for the points given by explicit coordinates. Note that labels are given without quotes, while the additional letter after the weight must be written between single quotes. An example of a path for the fcc lattice:

7
gG   20   
X    20
W    20  'gS1'
1.0 1.0 0.0 20 'X'
gG    0
gG   20   
L     0

This path has five lines, the first from 1#1 to X with 20 points, the second from X to W (that in the plot will have the label 2#2 ) with 20 points, the third from W to the point of coordinates (1.0, 1.0, 0.0) (that in the plot will have the label X ), the fourth from (1.0, 1.0, 0.0) to 1#1 with 20 points and a final line from 1#1 to L with 20 points. Until version 1.8.1 labels are read as three characters, so it is important not to write the weights too close to the labels. Grüneisen parameters are not analytic at the 1#1 point so to obtain a correct plot, the 1#1 label in the middle of a plot must be repeated twice, as in the example.