From owner-chemistry*- at -*ccl.net Tue Aug 26 14:02:00 2008 From: "Yuanyuan Cui wicky.cc * gmail.com" To: CCL Subject: CCL:G: ONIOM calculation errors. Help! Message-Id: <-37632-080826125009-26147-Z14ZLPry3+EE7fzEMGp6rw-*-server.ccl.net> X-Original-From: "Yuanyuan Cui" Date: Tue, 26 Aug 2008 12:50:05 -0400 Sent to CCL by: "Yuanyuan Cui" [wicky.cc*gmail.com] I'm doing a 2-layer ONIOM calculation. My ligand are two Zinc ions are set to the high layer (rhf/6-31g*) and 16 residues from the protein active site around this ligand are set to low layer (i tried amber and am1). I deleted the backbone of the residues and added H for the valence. But I met several problems with this setting. 1. I used gaussview3 to prepare the input file for ONIOM. It works ok for the high layer, but after I set the charge for the low layer to be -2 (two Asp in the low layer), it can't let me to set the multiplicity to be 1 (it only provides the options of 2, 4, etc). This happens for both amber and am1. If I change the multiplicity to be 1 manually in the gaussian input file it generated, it will complain can't combine multiplicity 1 with 258 electrons. What could be the problem of this? 2. When I tried to run with multiplicity to be 2 and use am1 for the low layer, it ran for about one day and got error complaining "unable to achieve self-consistence". I have used SCF(maxcycle=2000). How can I solve this problem? 3. When I tried to run low layer using amber, it keeps complaining "Missing atomic parameters for atom 204". How can I know what parameters it missing and how can I add those parameters? I really appreciate your help! Yuanyuan Cui wicky.cc|-|gmail.com Cambridge, MA USA