# [Pw_forum] which is the local potential

wujianchun jcwu.suda at hotmail.com
Sun Nov 1 12:11:30 CET 2009


Dear Paolo and Stefano,

That's very helpful Indeed,  Thanks a lot!

Regards

Jianchun Wu

PhD candidate

Department of Phyiscs, Soochow University, China

From: baroni at sissa.it
To: pw_forum at pwscf.org
Date: Sun, 1 Nov 2009 11:56:41 +0100
Subject: Re: [Pw_forum] which is the local potential

one further reason why the bare+Hartree potential should be used for estimating the value of the potential in the vacuum far from a surface (or from a molecule), even if the simple LDA is used, is that the exchange potential tends to zero as (\rho)^{1\over 3}, while the Hartree+bare potential tends to zero as \rho, hence faster.
SB

On Nov 1, 2009, at 9:11 AM, Paolo Giannozzi wrote:

On Oct 31, 2009, at 10:23 , wujianchun wrote:

The question is which one, 1 total potential V_bare+V_H+V_xc,

11 the V_bare+V_H potential or 12 the electric field potential in

plot_num, corresponds the above-mentioned "local potentials"?

definitely not 12; the local potential is 1. The case "11" is useful
to calculate the average potential far from a surface (e.g. for
work function calculation) since the XC potential has often a
nasty behavior when the charge density vanishes

PS: which is the unit of the potentials in the outfiles, eV or Ry?

Ry

P.
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Paolo Giannozzi, Dept of Physics, University of Udine
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