From owner-chemistry@ccl.net Sat Mar 31 07:58:00 2012 From: "Christopher Cramer cramer|*|umn.edu" To: CCL Subject: CCL: =?windows-1252?Q?Re=3A_CCL=3A_=93Best=94_atomic_charge_model?= Message-Id: <-46611-120331075417-4496-RPaueXYMWd4vrqJv/+q6ug#server.ccl.net> X-Original-From: Christopher Cramer Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=windows-1252 Date: Sat, 31 Mar 2012 06:54:06 -0500 Mime-Version: 1.0 (Apple Message framework v1084) Sent to CCL by: Christopher Cramer [cramer:+:umn.edu] Sebastian, I might say that the question, "What is the best partial atomic charge model?" is in some sense incomplete -- or at least open to faith-based responses, as there is no universally accepted measure of "best". A more complete formulation would be, "What is the best partial atomic charge model to [do something that can be quantitatively asessed]?" (much as the paper you cite below emphasized through its title). In our own work, we've taken [do something that can be quantitatively asessed] to be "reproduce the correct molecular electric dipole moment through distributed monopoles" and that has led to the CMx series of charge models, the most recent one of which was published as Marenich, A. V.; Jerome, S. V.; Cramer, C. J.; Truhlar, D. G. "Charge Model 5: An Extension of Hirshfeld Population Analysis for the Accurate Description of Molecular Interactions in Gaseous and Condensed Phases" J. Chem. Theor. Comput. 2012, 8, 527 (doi:10.1021/ct200866d). But, in spite of conventional partisanship, I would certainly accept that other charge models might have greater utility for other purposes to which they are planned to be put. Best regards, Chris On Mar 31, 2012, at 3:00 AM, Sebastian Kozuch kozuchs-*-yahoo.com wrote: > > Sent to CCL by: Sebastian Kozuch [kozuchs^yahoo.com] > Dear all, > I've just read the article "What is the “best” atomic charge model to describe through-space charge-transfer excitations?" (Phys. Chem. Chem. Phys., 2012, 14, 5383) > My question is quite traditional: Is there any atomic charge model (Mulliken, Lowdin, Bader, NPA, etc) that can give reliable results on a wide variety of properties? It is known that absolute charge values are useless, but at least a method that provides consistent relative would be nice. I had too many bad experiences trying to understand the charges on complexes with several partition schemes. > > I know that several books already discussed this, and I'm sure this is not the first time this is asked in CCL, but I would like to know the "state of the art" opinion from the people that deal with this professionally. > > Best, > Sebastian> > -- Christopher J. Cramer Elmore H. Northey Professor University of Minnesota Department of Chemistry 207 Pleasant St. SE Minneapolis, MN 55455-0431 -------------------------- Phone: (612) 624-0859 || FAX: (612) 626-7541 Mobile: (952) 297-2575 email: cramer..umn.edu twitter: ..ChemProfCramer http://pollux.chem.umn.edu (website includes information about the textbook "Essentials of Computational Chemistry: Theories and Models, 2nd Edition")