From martin $#at#$ qtp.ufl.edu Fri Sep 26 01:26:44 1997 Received: from qtp.ufl.edu for martin.,at,.qtp.ufl.edu by www.ccl.net (8.8.3/950822.1) id AAA17338; Fri, 26 Sep 1997 00:39:33 -0400 (EDT) Received: from visi2.qtp.ufl.edu by qtp.ufl.edu (SMI-8.6/SMI-SVR4) id UAA22278; Thu, 25 Sep 1997 20:09:49 -0400 Received: by visi2.qtp.ufl.edu (SMI-8.6/SMI-SVR4) id UAA01013; Thu, 25 Sep 1997 20:10:24 -0400 Date: Thu, 25 Sep 1997 20:10:24 -0400 Message-Id: <199709260010.UAA01013;at;visi2.qtp.ufl.edu> From: Charles & To: cramer |-at-| pollux.chem.umn.edu (Christopher Cramer) Cc: chemistry[ AT ]www.ccl.net Subject: CCL:M:Charges and dipole moments (fwd) In-Reply-To: <199709251941.OAA25207&$at$&pollux.chem.umn.edu> References: <199709251941.OAA25207 \\at// pollux.chem.umn.edu> Re below discussion on charges: > > Quite the contrary -- a charge model can do better than the underlying > wave function if it is DESIGNED to do so (what we have coined a Class IV > charge model). The CM1 charge model (reference Storer, J. W.; Giesen, D. > J.; Cramer, C. J.; Truhlar, D. G. " Class IV Charge Models: A New > Semiempirical Approach in Quantum Chemistry" J. Comput.-Aid. Mol. Des. > 1995, 9, 87. available on the web at > http://www.ibc.wustl.edu/jcamd/278/paper.html) is a mapping procedure that > takes lower quality charges (e.g., semiempirical ZDO Mulliken) and converts > them to very high-quality charges that reproduce experiimental dipole > moments better than the expectation value of the dipole moment operator > acting on the semiempirical wave function. > It is very interesting that this can be done. I am curious if anyone has tried to fix up the semiempirical dipole moment operator rather than the charges themselves. After all, an exact semiempirical dipole moment operator should really be parameterized to include corretaion effects. With Best Regards Chuck Martin ---------------------------------------------------------- Charles H. Martin Quantum Theory Project University of Florida Gainesville, FL 32606 martin*- at -*qtp.ufl.edu ----------------------------------------------------------