[Wien] :ENE units

[Stefaan Cottenier]

> >I suspect this may be due to my lack of understanding of what the total 
> >energy refers to, i.e. is it per formula unit, per unit cell,  relative to 
> >volume of unit cell determined by the lattice parameters, or some other 
> >factor I haven't considered.

The total energy is for the primitive unit cell, of which you find the value 
in :VOL (au^3).

> >The non-magnetic and ferromagnetic CrN unit cells are cubic, space group 
> >Fm-3m, with a = 4.1480 Angstroms, hence my case.struct file has two 
> >inequivalent atoms listed.
> >
> >The antiferromagnetic unit cell is orthorhombic, with a = 5.757, b = 
> >2.964, c = 4.134 Angstroms. To properly state a magnetic unit cell with 
> >spin-up and  spin-up chromium atoms, I have constructed a supercell with 8 
> >inequivalent atoms listed, and transform this with the space group P1.

In order to get rid of all possible numerical inaccuracies, it is recommended 
to calculate all structures in the same unit cell. In your case, you have to 
take your larges cell (the antiferromagnetic one), and do also the ferro- and 
nonmagnetic calculation in such a cell. Make also sure that all other 
parameters (Rmt, Rkmax, R0, Gmax, k-mesh, ...) are identical in all 
calculations. [that's even true for your current result: if you would have had 
a different Rmt in one of your smaller cells, that could easily lead to the 
observed discrepancy]

Stefaan