[CPMD-list] RMS gradient

[Keta Jones]

Dear Prof Hutter,
Many many thanks for your clarification. Still I want
to ask is this procedure is applicable during both
the Geometry Optimization abd Molecular Dynamics
scheme.If I am right, then this convergence can be
checked from GNMAX/GEMAX values from output file.
Suppose I want to get a optimized structure (Roughly)
of pyridine dimer by Geometry Optimization(First
method) and by ab Molecular Dynamics simulation(Second
methos). Then can I confirm the convergence by just
looking at GNMAX/GEMAX values. Which way will be
better to get a optimized geometry i.e. by only
OPTIMIZE GEOMETRY or MOLECULAR DYNAMIC or BOTH.

Thanks again,
keta

--- Juerg Hutter <hutter at pci.unizh.ch> wrote:

> Hi
> 
> The root mean square
> (see
> http://mathworld.wolfram.com/Root-Mean-Square.html)
> is a measure for the size of a distribution. We use
> it
> to give a size of the electronic gradient during the
> minimization. The optimized energy is found for
> the case of zero gradient. Numerically this is
> monitored
> by the RMS value of the gradient.
> However, there is a second measure, the largest
> absolute
> value of an element of the gradient.
> In CPMD both measures are printed, side by side in
> the
> output. Convergence is checked wrt the largest
> gradient
> element. Convergence is assumed if this value
> falls below a threshold (default 10^-5).
> 
> regards
> 
> Juerg Hutter
> 
>
----------------------------------------------------------
> Juerg Hutter                   Phone : ++41 1 635
> 4491
> Physical Chemistry Institute   FAX   : ++41 1 635
> 6838
> University of Zurich           E-mail:
> hutter at pci.unizh.ch
> Winterthurerstrasse 190
> CH-8057 Zurich, Switzerland
>
----------------------------------------------------------
> 
> 
> On Tue, 25 Jan 2005, Keta Jones wrote:
> 
> > Please help me to explain the significance of
> "Root
> > mean square gradient" for energy minimization of
> > systems.How can I check this from CPMD output file
> ?
> >
> > regards
> > keta
> >
> > =====
> > Keta
> >
>
**************************************************************************************
> >
> >
> >
> >
> > __________________________________
> > Do you Yahoo!?
> > Yahoo! Mail - You care about security. So do we.
> > http://promotions.yahoo.com/new_mail
> > _______________________________________________
> > CPMD-list mailing list
> > CPMD-list at cpmd.org
> > http://cpmd.org/mailman/listinfo/cpmd-list
> >
> 



	
		
__________________________________ 
Do you Yahoo!? 
Yahoo! Mail - You care about security. So do we. 
http://promotions.yahoo.com/new_mail