Paul, The units are (a.u.)^-3. If you sum up all the values on the real-space grid and multiply by the volume element dV in atomic units you should get the number of electrons in the unit cell. (dV = V/Nx/Ny/Nz, where V is the unit cell volume, Nx, Ny, Nz are dimensions of the real-space grid).
Best regards, Andrei On Tue, Oct 2, 2012 at 9:14 PM, W2AGZ <w2agz at w2agz.com> wrote: > To All, > > > > I think I know the answer to this question, but I?d like an expert opinion, > nonetheless. > > > > What are the units of ?isosurface? plotted by XCrySDen using output from > pp.x passed through a .xsf file? I suspect it?s something like > > normalized total cell charge (i.e., ?e=1 times the number of filled non-core > pseudo-orbitals per unit cell) divided by a.u.^2. Suppose I have a > structure I?m examining with XCrySDen with max/min values, let?s say > (+3,-1), and I select +0.25. What exactly is this number in ?The Creator?s > Units,? sometimes known as SI. I?ve poured through the source code of > chdens.f, but get lost trying to guess the pneumonic of each variable. > > > > Seriously, I?m writing up a paper comparing the distribution of charge in > various (n,m) carbon nanotubes, and want to avoid dumb errors. > > > > Thanks, > > > > Paul Grant > > W2AGZ Technologies > > Associate Staff, JPL/NASA/CalTech > > > > > > > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum
