From owner-chemistry@ccl.net Fri Aug 8 10:15:00 2008 From: "Simon Halstead shalstead(a)hit.edu.cn" To: CCL Subject: CCL: Ab initio on bridged rings Message-Id: <-37521-080807214545-1766-3FRcnFRPqRi+DtYSc45Xhg:_:server.ccl.net> X-Original-From: Simon Halstead Content-Type: text/plain; charset=us-ascii Date: Fri, 8 Aug 2008 01:45:27 +0000 (GMT) MIME-Version: 1.0 Sent to CCL by: Simon Halstead [shalstead:hit.edu.cn] Dear all, Thanks for the replies. First of all, I did perform an initial calculation on the structures at pm3 level. The calculations were quick and located the stationary point. Here are the coordinates for one of the structures: 22 C 0.3278408383 0.2556632257 -0.6958480605 C -0.6749330239 -0.8804489119 -0.6637892896 C -1.9925684835 -0.1640159207 -0.9990405167 C -1.7766055437 0.8451058680 0.2241238684 C -0.4411950377 1.4743937219 -0.1151303166 C -1.5534544981 -0.1580831322 1.3412477527 C -0.8667997706 -1.1855423421 0.8239710266 C 1.7051382469 -0.0777886638 -0.1199445501 C 2.6193671392 1.0431733002 0.3616649580 O 2.0929414634 -1.2296044956 -0.1029624608 H -2.8775370468 -0.7968676192 -0.8864627204 H -1.9667233161 0.3565767738 -1.9434479163 H -1.7811465980 0.0168100327 2.3851269590 H -0.4303225256 -2.0227098365 1.3505314534 H -2.6065279205 1.5190592093 0.3872605483 H -0.4083901218 -1.7381098498 -1.2646540978 H -0.5730139012 2.2617625045 -0.8428063319 H 0.0092293900 1.8939641578 0.7693408676 H 0.5599560611 0.4970449650 -1.7524902275 H 3.5406839415 0.6093501882 0.7475333961 H 2.8549606891 1.7285215964 -0.4508702454 H 2.1443540827 1.6275360285 1.1469846166 Thanks again for your help, Simon Halstead ----- Original Message ---- > From: errol lewars elewars+*+trentu.ca To: "Halstead, Simon " Sent: Wednesday, August 6, 2008 4:25:25 AM Subject: CCL: Ab initio on bridged rings Sent to CCL by: errol lewars [elewars||trentu.ca] 2008 August 05 Could you give us the structure (cartesians) of one (preferably the smallest) of your troublesome conmpounds)? E. Lewars ============= Simon Halstead shalstead . hit.edu.cn wrote: >Sent to CCL by: "Simon Halstead" [shalstead:hit.edu.cn] > >Dear all, > >I am trying to optimize some bridged (1-4) cyclohexane rings. I initially optimized them using sempiempirical methods. These calculations converged very rapidly. However, I then tried to optimize the resulting structures at a higher level of theory. These high level calculations have failed to converge, despite being run for a large number of steps. I have tried HF, MP2 and B3LYP with a variety of basis sets but nothing appears to converge. Visualizing the outputs of the failed calculations shows no problems with the structure. >Does anyone have any experience with structures like this or can anyone give me a suggestion of how best to optimize bridged rings? >I am using GAMESS if this makes any differnce. > >Thanks for your help, > >Simon Halsteadhttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp://www.ccl.net/spammers.txt