From owner-chemistry@ccl.net Thu Jul 8 02:48:00 2010 From: "Ugur Mart ugurmart|*|yahoo.com" To: CCL Subject: CCL: Force field types and potential Message-Id: <-42260-100708002907-12837-EYzDy1PlYpuGoNN37fB/BA(_)server.ccl.net> X-Original-From: Ugur Mart Content-Type: multipart/alternative; boundary="0-1394139601-1278563307=:30613" Date: Wed, 7 Jul 2010 21:28:27 -0700 (PDT) MIME-Version: 1.0 Sent to CCL by: Ugur Mart [ugurmart.:.yahoo.com] --0-1394139601-1278563307=:30613 Content-Type: text/plain; charset=us-ascii Dear Members There are several types of force fields and potentials which seems confusable to decide to use for the simulations. Even for the similar systems different force fields and potentials may be used as appears in the published papers. Can anyone please suggest a useful source for which force fields types and potentials can be used for what kind of molecular systems, pros and cons and validity of the FF types and potential? For instance some says CVFF or UFF have not been used much longer. But why and what is merit of the others? Regards U. Martin --0-1394139601-1278563307=:30613 Content-Type: text/html; charset=us-ascii

Dear Members

There are several types of force fields and potentials which seems confusable to decide to use for the simulations. Even for the similar systems different force fields and potentials may be used as appears in the published papers.
Can anyone please suggest a useful source for which force fields types and potentials can be used for what kind of molecular systems, pros and cons and validity of the FF types and potential? For instance some says CVFF or UFF have not been used much longer. But why and what is merit of the others?

Regards

U. Martin

--0-1394139601-1278563307=:30613-- From owner-chemistry@ccl.net Thu Jul 8 15:17:00 2010 From: "W. Flak williamflak-*-yahoo.com" To: CCL Subject: CCL: AIM Bond Critial point Message-Id: <-42261-100708151459-12160-HSWboc7Wh0V/WCo+cpJP2Q(a)server.ccl.net> X-Original-From: "W. Flak" Date: Thu, 8 Jul 2010 15:14:58 -0400 Sent to CCL by: "W. Flak" [williamflak*|*yahoo.com] Dear CCL During AIM calculations on some molecules, I got across a structure in its molecular graph there is a bond critical point between two atoms, but this bond critical point doesn't exist in its virial graph, on the another hand, I got the opposite case, a bond critical point in virial graph but not in molecular graph. I couldn't find any reference for these two cases, or what they mean in the chemical sense. I would be grateful if you could help me and direct me to a reference discussing these issues. Thanks in advance W. Flak From owner-chemistry@ccl.net Thu Jul 8 19:05:01 2010 From: "G. Gopakumar scschem[]gmail.com" To: CCL Subject: CCL: AIM Bond Critial point Message-Id: <-42262-100708171217-32138-SJ35gl5Imeg2A5y1+np5eA .. server.ccl.net> X-Original-From: "G. Gopakumar" Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="UTF-8" Date: Thu, 08 Jul 2010 23:12:07 +0200 Mime-Version: 1.0 Sent to CCL by: "G. Gopakumar" [scschem[a]gmail.com] Hi, Check whether Pincare-Hobf relationship is valid in your case: n-b+r-c=1 n = number of attractors b = number of bond critical points r = number of ring critical points c = number of cage critical points if no, then you have to adjust some parameters to locate the bond critical point. which program did you use to plot these data? if it is AIM2000 I suppose you then have to define a cube, with some non default starting values along the side and iterate. I hope then you will be able to locate this bcp. regards -Gopakumar On Thu, 2010-07-08 at 15:14 -0400, W. Flak williamflak-*-yahoo.com wrote: > Sent to CCL by: "W. Flak" [williamflak*|*yahoo.com] > Dear CCL > During AIM calculations on some molecules, I got across a structure in its > molecular graph there is a bond critical point between two atoms, but this bond > critical point doesn't exist in its virial graph, on the another hand, I got > the opposite case, a bond critical point in virial graph but not in molecular > graph. I couldn't find any reference for these two cases, or what they mean in > the chemical sense. I would be grateful if you could help me and direct me to a > reference discussing these issues. > Thanks in advance > W. Flak> > -- __________________________________________________________ Dr. G. Gopakumar Postdoctoral Researcher, Section of Theoretical Chemistry, Department of Chemistry & Pharmaceutical Sciences, Faculty of Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands