Subject: Re: CCL:Line minimization failed twice

From: "James J. P. Stewart" <jstewart=at=us.fujitsu.com>
Date: Mon, 29 Nov 2004 16:48:06 -0700

Geometry optimization in MOPAC proceeds by a series of line 
minimizations.  If the line search can't find a point that is lower than 
the starting point of the line search, then an error must have occurred (in 
the algorithm), and the warning message is printed.

This occurs only in the BFGS optimizer - more recent versions of MOPAC use 
Baker's EF by default - it's more robust.

I hope this helps.

Jimmy

At 02:43 PM 11/29/2004, Axel Mathieu wrote:
>Greetings,
>
>I've been trying out some PM3 and AM1 calculations on some of my molecules 
>and have obtained the following "error" in some of the log files:
>
>THE LINE MINIMIZATION FAILED TWICE IN A ROW.   TAKE CARE!
>      SCF FIELD WAS ACHIEVED
>
>I understand that this has already been asked before on CCL (even up to 
>1995) and have found solutions to it in the archives (reference: 
><http://www.ccl.net/cgi-bin/ccl/message.cgi?1995+08+09+008>http://www.ccl.net/cgi-bin/ccl/message.cgi?1995+08+09+008 
>). However, it does not explain the source of this error. I'm relatively 
>new to MOPAC and would appreciate your help in aiding me to understand the 
>meaning of this. How does "minimization" fail twice in a row?
>
>Many thanks,
>
>APM
>

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