Monthly Archives: August 2013

now for different supercomputers

I already shared my now script intended for a small “in home” computing cluster. This time, I am sharing two other variations of that script, designed for the queuing systems of two different supercomputers: Mare Nostrum at BSC, Juropa at JSC and HLRN.

Both of them are the predecessors of the newer now script, and they only have the very basic features, but if you need an script that works right out of the box for any of the supercomputers mentioned above, this is the quick solution.

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pw2cellvec: monitor vc-relax convergence in QE

When running a cell relaxation, it is sometimes nice to monitor what is going on with the cell parameters. If you run the cell relaxation with Quantum Espresso, you can use my python script “pw2cellvec” to parse all the information you need.

So, first of all, run a “vc-relax” calcuculation with a large (about 2 times bigger) cutoff for both wavefunction (ecutwfc) and charge (ecutrho) and wait for a couple of iterations. These calculations are very expensive, due to the large cutoffs.

Then, just run the script and you will get something like this:

user> -o pwout
- -
AA a= 6.02104498011 b= 6.02109150665 c= 9.45688483193 Vol.= 296.919819153
au a= 11.3781260524 b= 11.3782139748 c= 17.8709224124 c/a= 1.57063846279
alpha= 89.9989981833 beta= 90.0012313781 gamma= 119.99694776
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pw2gap: Quick Homo/Lumo gap check for QE

In order to check the Homo/Lumo gap from a Quantum Espresso (pw.x) calculation it is possible to plot the Density Of States and estimate the distance of empty states around the Fermi level (E=0), but what about if we only want a numerical (accurate) value?
This can be done very quick with “pw2gap” script, which can be downloaded from here.

It goes trough all the eigenvalues at the end of the output, including the case of spin-polarization (spin up/down) and k-points, and it simply prints the energies of the HOMO and LUMO orbitals as well as, of course, the difference between them. As simple as that.

It looks like this (for the example of the wustite):

user> -o pwout
HOMO= 9.4503 LUMO= 11.5898 eV
H/L GAP = 2.1395