On Sun, Jul 22, 2012 at 10:55 PM, sylvian <sylviankahane at gmail.com> wrote:
> cp.x is printing an Etot at the end of the run (in my case something like > -47 Ha). Taking its state at the end of the run, i.e. ions positions and > charge density, as an input to pw.x (admittedly with a different > pseudopotential) I am getting a "total energy" differing by an order of > magnitude (in my case -800 Ry). > > > Dear Sylvan, absolute energies have no meaning in general. There can be some more or less natural choices for a zero energy, but n periodic boundary conditions and with pseudopotential there is none that really makes sense. It is also true that with fairly similar pseudopotential you often get similar (if equally meaningless) "total" energies. You are not specifying which pp's you're using so I can only guess: 1. the pp used in pw.x has more valence electrons 2. the pp used in pw.x is actually a paw dataset, and you are comparing the all-electron energy with the valence one best regards -- Lorenzo Paulatto IdR @ IMPMC/CNRS & Universit? Paris 6 phone: +33 (0)1 44275 084 / skype: paulatz www: http://www-int.impmc.upmc.fr/~paulatto/ mail: 23-24/4?16 Bo?te courrier 115, 4 place Jussieu 75252 Paris C?dex 05 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120722/81c41ff5/attachment.htm -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: image/jpeg Size: 10569 bytes Desc: not available Url : http://www.democritos.it/pipermail/pw_forum/attachments/20120722/81c41ff5/attachment.jpeg
