From owner-chemistry@ccl.net Fri Feb 13 17:06:01 2009 From: "Roman D Gorbunov rgorbuno^_^aecom.yu.edu" To: CCL Subject: CCL:G: Hessian matrix in Cartesian coordinates by Gaussian. Message-Id: <-38612-090213170249-14902-U+SVJjY7jCqa4B1UKx5tBw:-:server.ccl.net> X-Original-From: "Roman D Gorbunov" Date: Fri, 13 Feb 2009 17:02:45 -0500 Sent to CCL by: "Roman D Gorbunov" [rgorbuno(0)aecom.yu.edu] Dear CCL Subscribers, I need to calculate the Hessian matrix in Cartesian coordinates. I searched for the answer in the Interned found this: http://www.ccl.net/chemistry/resources/messages/2005/10/03.007-dir/ It is written that first I have to calculate the checkpoint file. Then I have to use "formchk name.chk name.fchk" to get a formated file. And finally I have to use a script called "demofc" to extract the Hessian matrix given in the Cartesian coordinates. I have a problem with the last step. I do not know how exactly should I use the "demofc". I also cannot find any useful information about that. Could anybody pleas help me with that? By the way, I checked the formated checkpoint file (name.fchk). It contains some information about the system, but I did not find there anything about Hessian matrix. May be I have to put some additional keywords into the Gaussian input file to force Gaussian to calculate the Hessian matrix? Roman