[Pw_forum] npt with |zeta| > 1

[Paolo Giannozzi]

On Tuesday 06 April 2004 18:54, Dariusz Chrobak wrote:

> I'm a new Pwscf user. I have seen the following information during scf run:
>
>   npt with |zeta| > 1:    76986, npt tot   364500,     21.12 %
>
>   npt with rhoup < 0:       32, npt tot   364500,      0.01 %
>
> Is it wrong message?

no, the message is correct :-)

> If yes what should I do to avoid this problem? What mean "zeta"?

it is likely that there is no real problem. With ultrasoft pseudopotentials,
the charge density may have very small negative values. It usually
happens with molecules in the empty space, it is usually harmless,
it disappears with a higher cutoff for the charge density (ecutrho). 
Zeta is the spin polarization:
zeta = (rho(up) - rho(down)) / (rho(up) + rho(down)

Paolo

-- 
Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
Scuola Normale Superiore    Phone:   +39/050-509876, Fax:-563513 
Piazza dei Cavalieri 7      I-56126 Pisa, Italy