Density of states and np dimensions

               I've started learning about plane-wave DFT last month. My goal is to perform density of state calculations so I tried out the following NWChem example : http://nwchemgit.github.io/index.php/Plane-wave_Density_Functional_Theory#Using_BAND_to_Calculate_the_Density_of_States_of_Diamond. The diamond-dos.dos was created in the perm directory. I've figured out that the first column of this file gives the energy in Hartree units and the second column is the density of states(DOS) and thus was able to generate the DOS plot that looks identical to the one on the web page. However, I have been trying unsuccessfully to find the units of the DOS. Firstly, is the latter defined as the number of one-electron states divided by the energy range (E,E+delta_E)/delta_E (cf. "SOLID STATE PHYSICS" by Ashcroft and Mermin)? If so what are the units of the one-electron energies? 

                 Secondly, can anyone tell me what the field "np_dimensions" is? According to "Hard scaling challenges for ab initio molecular dynamics in NWChem:Using 100,000 cpus per second", np stands for the number of processors and npi/npj stands for the size of column(row) processor group. In NWChem, the directive is given as NP_DIMENSIONS <integer npi npj default -1 -1>. Do they correspond to the ones in the article? Lastly, the Nickel example gives the following input: np_dimensions -1 -1 4. What does 4 represent?

                  Thank you very much for your help.