[Pw_forum] calculation wouldn't run using espresso-4.2.1 but did run with espresso-4.1.3

[Paolo Giannozzi]

On Mar 8, 2011, at 24:28 , Tram Bui wrote:

> I have post a question regarding the single atom calculation
> for carbon simple cubic system last month [...] the calculation
> ran fine using espresso-4.1.3 (older version), but not for
> espresso-4.2.1 (latest version)

the old version used to symmetrize tha charge density also
for the Gamma case. The new version doesn't (it shouldn't
be needed in principle). The problem is that in the specific
case of atoms, you may have degenerate levels. The
resulting charge density is in general not spherical.  If you
force it top be spherical, the code quickly converges to
a solution. If you don't, it doesn't. This is a problem that
arises only in isolated atoms, so I wouldn't attach much
importance to it. And no, it is not a bug, contrary to what
I said in a previous message.

Paolo
---
Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222