Hi,
On Monday, October 18, 2010, sunita gupta wrote:
> QMMM: WARNING!
> QMMM: Unable to achieve self consistency to the tolerances specified
> QMMM: No convergence in SCF after 1000 steps.
> QMMM: Job will continue with unconverged SCF. Warning energies
> QMMM: and forces for this step will not be accurate.
> QMMM: E = -0.1752E+07 DeltaE = 0.3029E-05 DeltaP = 0.1034E-07
> QMMM: Smallest DeltaE = -0.1765E-06 DeltaP = 0.4715E-07 Step = 20
The good news: This isn't really an error, but just a warning, so the
calculation keeps going. If this keeps happening, then it can be a
real problem. One possible reason for this behavior may be that some
waters in the QM zone are diffusing away, and then the SCF gets harder
and harder to converge. Have you tried following the QM waters in a
visualization software, like VMD?
Now the bad news: if this is indeed what is happening, at the moment,
there's no way to avoid it other than restraining the waters. We are
currently working on an algorithm to deal with that, but it's still in
development and won't bout at least until the next version of Amber.
HTH,
Gustavo.
--
Gustavo Seabra
Professor Adjunto
Departamento de Química Fundamental
Universidade Federal de Pernambuco
Fone: +55-81-2126-7417
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Received on Mon Oct 18 2010 - 05:30:05 PDT
