CCL: Ab initio on bridged rings

 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 <owner-chemistry^ccl.net>
 To: "Halstead, Simon " <joyjoyhappyjoy^yahoo.co.uk>
 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