From chemistry-request ":at:" server.ccl.net Thu Dec 20 17:42:35 2001 Received: from adenine.cgl.ucsf.edu ([128.218.27.3]) by server.ccl.net (8.11.6/8.11.0) with ESMTP id fBKMgZS04124 for ; Thu, 20 Dec 2001 17:42:35 -0500 Received: from adenine.cgl.ucsf.edu (localhost [127.0.0.1]) by adenine.cgl.ucsf.edu (8.12.1/8.12.1/GSC1.10) with ESMTP id fBKMg7fc669495; Thu, 20 Dec 2001 14:42:07 -0800 (PST) Received: (from ross "-at-" localhost) by adenine.cgl.ucsf.edu (8.12.1/8.12.1/Submit) id fBKMg58b669490; Thu, 20 Dec 2001 14:42:05 -0800 (PST) Date: Thu, 20 Dec 2001 14:42:05 -0800 (PST) From: Bill Ross Message-Id: <200112202242.fBKMg58b669490-!at!-adenine.cgl.ucsf.edu> To: chemistry[ AT ]ccl.net, nahoko[ AT ]nandomail.com Subject: Re: CCL:LJ forcefield for K+ does anybody has a LJ potential for the K+ cation, I want to simulate an aqueous solution containing the K+ ion. I know of a reference Physica B & C 1985, 131, 196, but it is out of reach. It depends on the water model, and also on the combining rules used for mixing the LJ with the water LJ. See Ross, W.S. and Hardin, C.C., J. Am. Chem. Soc. 116, 6070-6080 (1994). We discovered that various parameters seem to work equally well. The commonly-used parameters for K+ are those of Aqvist, but simpler ones give indistinguishable results for free energy and radial distribution. We also had to convert the Aqvist parameters for use with the combining rules used in the Amber programs. And different parameters were necessary for ion interactions with non-TIP3 atoms. Bill Ross