Subject: Elimination of negative force constant

From: "pankratov" <[email-masked]>
Date: Thu, 4 Jul 96 12:07:27 +0400

July 4, 1996

Professor Nancy Teich
The DASGroup, Inc.
P. O. Box 5428
Johnstown, PA 15904-5428

   Dear Professor Nancy Teich,
   In addition to valuable advice  by Professor Stephen B. Bowlus,
Sandoz Agro, Inc.,  according to our small experience, the ways to
avoid a negative force constant appearance,  as well as to reach a
sufficient gradient norm decrease, consist in using NLLSQ (as Pro-
fessor  Sharifuddin Mohd Zain,  Jabatan Kimia,  University Malaya,
considers),  the latter  often  increasing  the computational time
drastically,  and also applying  NOTHIEL, DFP,  or NOTHIEL and DFP
together.
                                                   Sincerely yours
                                                  Alexei Pankratov

Professor Dr. Sc. Alexei N. Pankratov
Department of Chemistry
N. G. Chernyshevskii Saratov State University
83 Astrakhanskaya Street, Saratov 410071, Russia
Fax: ++7 (8452) 24-04-46
E-mail: [email-masked]
Web: http//:www.ssu.runnet.ru