Essentially the PROCAR file is very similar to the EIGENVAL file in that it contains each band energy for each k-point. However, the additional information contained in the PROCAR is that via atomic orbital projections, VASP will estimate which atoms and which orbitals contribute to which eigenvalues. An example of this is that it can allow you to have a site projected band structure (just like the additional information in the DOSCAR allows you to do site projected density of states). For the most part, the PROCAR file is well labelled in that it is organized  in blocks by k-point, and then by eigenvalue, and for each eigenvalue it lists the ions in order of your POSCAR. Across each row is the fractional breakdown of each orbital component for the given atom (in the order s, py, pz, px, dxy, dyz, dz2, dxz, dx2, and total). It should be noted that this is the same order that the DOSCAR atomic projections are given in. In the case of spin polarization you should have a spin majority and spin minority column for each. As for a program that can plot with this information, one that comes to mind is p4vasp (http://www.p4vasp.at/), however I'm sure others exist as well.

 Hi, I do have a question regarding the projected band structure. Do I need an additional script to generate that plot, or how can I get it. What I would actually like to have is a the band structure plot in which I can differentiate the contribution of each type orbital.

Any help I will really appreciate it.

The script that I've been using doesn't currently plot the orbital contributions on the band structure, however there are several freely available tools that will do this for you. A few of the ones that I know are:

http://gvallver.perso.univ-pau.fr/?p=587

http://www.p4vasp.at/

and a few others here (https://www.vasp.at/index.php/resources)

The first one is probably the most straightforward to use for what you want while the others may have a bit more learning curve since they're larger programs.

Dear Andrew O'Hara,

Can you please tell me about how to calculate the parity of a particular band from the data obtained from PROCAR file. suppose i have the data like the following..

ion      s     py     pz     px    dxy    dyz    dz2    dxz    dx2    tot

  1  0.001  0.000  0.012  0.000  0.000  0.000  0.013  0.000  0.000  0.026

  2  0.001  0.000  0.011  0.000  0.000  0.000  0.013  0.000  0.000  0.025

tot  0.002  0.000  0.023  0.000  0.000  0.000  0.026  0.000  0.000  0.051

  1  0.000 -0.000 -0.000  0.000  0.000 -0.000  0.000  0.000 -0.000 -0.000

  2  0.000  0.000  0.000 -0.000 -0.000  0.000  0.000 -0.000  0.000  0.000

tot  0.000  0.000  0.000  0.000 -0.000 -0.000  0.000  0.000  0.000  0.000

  1 -0.000  0.000 -0.000 -0.000 -0.000 -0.000 -0.000 -0.000 -0.000 -0.000

  2  0.000  0.000  0.000  0.000  0.000 -0.000 -0.000  0.000 -0.000  0.000

tot -0.000  0.000 -0.000 -0.000 -0.000 -0.000 -0.000 -0.000 -0.000 -0.000

  1  0.001 -0.000  0.012 -0.000 -0.000 -0.000  0.013 -0.000 -0.000  0.026

  2  0.001 -0.000  0.011 -0.000 -0.000 -0.000  0.013 -0.000 -0.000  0.025

tot  0.002 -0.000  0.023 -0.000 -0.000 -0.000  0.026 -0.000 -0.000  0.051

I would be very thankful to you.

All the information from PROCAR file can be seen using the program p4vasp, there you can plot the states from element, orbital, or suborbital in the band structure.

For detailed explanation you can look https://www.vasp.at/wiki/index.php/PROCAR

you can take a look to https://romerogroup.github.io/pyprocar/index.html

it supports several other codes too