From chemistry-request -x- at -x- ccl.net Fri Jun 13 10:08:50 2003 Received: from mail.webcable.com.br (mail.webcable.com.br [200.189.175.162]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h5DE8kkr010325 for ; Fri, 13 Jun 2003 10:08:50 -0400 Received: from localhost ([127.0.0.1] helo=webcable.com.br) by mail.webcable.com.br with esmtp (Exim 3.36 #1) id 19QpJg-0006db-00; Fri, 13 Jun 2003 11:14:08 -0300 From: "Dinbmica" To: chemistry^at^ccl.net Subject: CCL: NDDO semiempirical parameters Date: Fri, 13 Jun 2003 11:14:08 -0300 Message-Id: <20030613111408.M52463^at^webcable.com.br> X-Mailer: Open WebMail 1.63 20020319 X-OriginatingIP: 200.183.85.218 (dinamica^at^webcable.com.br) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Dear CCLers,, I have a couple of questions about semiempirical parameters in NDDO methods (MNDO, AM1...): 1) Do you have any routine or the iterative formulas to obtain the derived parameters, rho1 and rho2, from the optimized ones (namely 1 center 2 electron integrals, g_ij, and zeta_i) ?? 2) Can you suggest any references which explicitly comment on the individual influence of the NDDO parameters upon calculated molecular properties? E.g.: If one varies the resonance integrals (beta_i), what is the effect upon geometries? Or if one varies the one center one electron integrals (U_ii), what is the effect upon charge distribution? Thank you very much for your help, Guilherme Menegon IQUSP