From owner-chemistry@ccl.net Wed Dec 15 10:34:00 2010
From: "=?utf-8?q?=C3=96d=C3=B6n_Farkas?= farkas]^[chem.elte.hu" <owner-chemistry^^^server.ccl.net>
To: CCL
Subject: CCL: Schematic optimization sequence
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Date: Wed, 15 Dec 2010 11:28:07 +0100
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Sent to CCL by: =?utf-8?q?=C3=96d=C3=B6n_Farkas?= [farkas^^^chem.elte.hu]
Hi Peter,

People (and it seems zou also) mix the geometry optimization and constructing 
the wavefunction for the molecule. Finding the appropriate wavefunction is 
many times a variational problem, therefore itself contains some sort of 
optimization. However, what you refer to as Berny optimization (Named after 
its "father" prof. H. Bernhard Schlegel) is geometry optimization and its 
goal to find a stationary point on the potential energy (hyper)surface, which 
is defined by the wavefunction and the total energy of the system. You can 
find his papers on his webpage: 
http://www.chem.wayne.edu/schlegel/Current/Schlegel.html
Unfortunately, other than the geometry optimization uses the gradient (first 
derivative of the energy with respect to atomic coordinates) and then 
predicts iteratively the position of the critical point until convergence 
(based on gradient and step size based limits) cannot be said on 
non-mathematical way about the process. If you have problems about the math 
involved I can help you but I cannot really gide you without involving at 
least some of the math concerned.

I hope I could help.

Best wishes,

Ödön

Odon Farkas
Associate Professor
Laboratory of Chemical Informatics
Institute of Chemistry
Eötvös Loránd University, Budapest
1/A Pázmány Péter sétány
H-1117 Budapest, Hungary
Cellphone: +36-30-2553111
On Monday 13 December 2010 13:28:37 P.D.Jarowski##surrey.ac.uk wrote:
> Hi, thanks to all for their helpful comments on previous posts!
>
> I would like to know if there are any online sources out there that
> describe in a didactic non-mathematical way how various computational ab
> initio sequences are caried out. Especially, for multireference methods.
> For example, what exactly in Berney optimization and how does is work
> within the scf procedure? I would love to have such a source for my
> students.
>
> Thanks,
>
> Best,
>
> Peter
> ***Sent via RoadSync® for Android™