From owner-nwchem-users@emsl.pnl.gov Mon Aug 30 14:47:18 2004 Received: from odyssey.emsl.pnl.gov (localhost [127.0.0.1]) by odyssey.emsl.pnl.gov (8.12.10/8.12.10) with ESMTP id i7ULlIFd029647 for ; Mon, 30 Aug 2004 14:47:18 -0700 (PDT) Received: (from majordom@localhost) by odyssey.emsl.pnl.gov (8.12.10/8.12.10/Submit) id i7ULlIq7029646 for nwchem-users-outgoing; Mon, 30 Aug 2004 14:47:18 -0700 (PDT) Date: Mon, 30 Aug 2004 14:47:15 -0700 From: Bill Schief Subject: tolguess in NWchem manual To: nwchem-users@emsl.pnl.gov Message-id: <4133A063.8030101@u.washington.edu> Organization: University of Washington MIME-version: 1.0 Content-type: multipart/alternative; boundary=------------070808060102060605090203 X-Accept-Language: en-us User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.4) Gecko/20011126 Netscape6/6.2.1 Sender: owner-nwchem-users@emsl.pnl.gov Precedence: bulk --------------070808060102060605090203 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit It would be helpful in the NWchem manual if the following lines would be printed in the DFT part, as well as the SCF part where they are now exclusively printed. These lines might help solve some convergence problems in DFT. For SCF, the initial Fock-matrix construction from the atomic guess is now (staring from version 3.3) performed to a default precision of 1e-7. However, other wavefunctions, notably DFT, use a lower precision. In charged, or diffuse basis sets, this precision may not be sufficient and could result in incorrect ordering of the initial orbitals. The accuracy may be increased with the following directive which should be inserted in the top-level of input (i.e., outside of the SCF input block) and before the TASK directive. set tolguess 1e-7 -- Bill Schief, Ph.D. Postdoctoral Fellow Department of Biochemistry Box 357350 University of Washington Seattle, WA 98195 Phone: (206) 543-9818 FAX: (206) 683-1792 schief@u.washington.edu --------------070808060102060605090203 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit It would be helpful in the NWchem manual if the following lines would be printed in the DFT part, as well as the SCF part where they are now exclusively printed. These lines might help solve some convergence problems in DFT.

For SCF, the initial Fock-matrix construction from the atomic guess is now (staring from version 3.3) performed to a default precision of 1e-7. However, other wavefunctions, notably DFT, use a lower precision. In charged, or diffuse basis sets, this precision may not be sufficient and could result in incorrect ordering of the initial orbitals. The accuracy may be increased with the following directive which should be inserted in the top-level of input (i.e., outside of the SCF input block) and before the TASK directive.

  set tolguess 1e-7

-- 
Bill Schief, Ph.D.
Postdoctoral Fellow 
Department of Biochemistry 
Box 357350 
University of Washington 
Seattle, WA 98195 

Phone: (206) 543-9818 
FAX:   (206) 683-1792 
schief@u.washington.edu

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