From owner-chemistry%!at!%ccl.net Wed Apr 26 11:24:00 2006 From: "Melanie Trusselle mt237(!)bath.ac.uk" To: CCL Subject: CCL:G: Gaussian problems Message-Id: <-31599-060426084519-22657-FghTnz87uRThZEpb/aHNEA/a\server.ccl.net> X-Original-From: "Melanie Trusselle" Date: Wed, 26 Apr 2006 08:45:17 -0400 Sent to CCL by: "Melanie Trusselle" [mt237]|[bath.ac.uk] Dear All, I am a new user of Gaussian and have encountered two problems that I have been unable to resolve. The first problem is the calculation of the energy barrier between two conformers. I am using QST2 for this and my input is below. %chk=QST2.chk %mem=500MB %nproc=1 pm3 Opt=QST2 find barrier for chair-boat interconversion 1 1 zmatrix of first structure 1 1 zmatrix of second structure This input gives the error message shown below: Symbolic Z-matrix: End of file in GetChg. Error termination via Lnk1e in /usr/local/g03/l101.exe at Tue Apr 25 14:53:45 2006. Job cpu time: 0 days 0 hours 0 minutes 2.1 seconds. File lengths (MBytes): RWF= 7 Int= 0 D2E= 0 Chk= 1 Scr= 1 I believe it relates to a lack of memory so I have tried changing %mem and have specifed extra memory when submitting the job but this has not solved the problem. I an aware that this question has been asked previously, and appologies for asking it again but there is no answer available. I am also interested in obtaining the J coupling constants for a molecule. I have used the following commands: nmr=SpinSpin b3lyp/6-31g(d) geom=connectivity An section of the output is: Total nuclear spin-spin coupling J (Hz): 1 2 3 4 5 1 0.000000D+00 2 0.482568D+02 0.000000D+00 3 0.581831D+02 0.557526D+01 0.000000D+00 4 0.167946D+03 -0.143914D+00 -0.160153D+01 0.000000D+00 5 0.107532D+01 0.576884D+02 -0.428170D+00 0.621590D+01 0.000000D+00 This is different from what I was expecting and I do not know how to relate it to my NMR specra or even if I have given the correct input. If anyone can advise me on these matters I would be most grateful. Thank you in advance. Melanie Trusselle mt237 a bath.ac.uk University of Bath, UK