From owner-chemistry-: at :-ccl.net Sun Dec 4 11:14:00 2011 From: "Sten Nilsson Lill stenil++chalmers.se" To: CCL Subject: CCL: How to calculate the independent degrees of freedom of a molecule? Message-Id: <-45980-111204111244-27756-0ir6vDILqiRVLmIOBThXlA]![server.ccl.net> X-Original-From: Sten Nilsson Lill Content-Language: en-US Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="us-ascii" Date: Sun, 4 Dec 2011 17:10:24 +0100 MIME-Version: 1.0 Sent to CCL by: Sten Nilsson Lill [stenil,chalmers.se] Hello Jun Zhang, I hope this paper by Pople and colleagues is helpful: J. A. Pople, Y. A. Sataty and E. A. Halevi, The Number of Independent Internal Coordinates in Symmetrical Molecules, Israel J. Chem. 19, 290 (1980). Hope it helps, Sten Ph.D. Sten Nilsson Lill Dep. of Chemistry University of Gothenburg SE-412 96 Gothenburg, Sweden e-mail: stenil,,chem.gu.se Phone: +46-31 786 9103 Fax: +46-31-772 3840 ________________________________________ > From: owner-chemistry+stenil==chem.gu.se,,ccl.net [owner-chemistry+stenil==chem.gu.se,,ccl.net] On Behalf Of Jun Zhang coolrainbow * yahoo.cn [owner-chemistry,,ccl.net] Sent: Saturday, December 03, 2011 2:11 AM To: Nilsson Lill, Sten Subject: CCL: How to calculate the independent degrees of freedom of a molecule? Hello everyone: For a nonlinear N-atom molecule there are 3N-6 internal degrees of freedom, of course. However, for a point group-constraint molecule, such as C2v H2O, there are only 2 independent degrees of freedom. So, is there a systematic way to determine the number and the contents of independent degrees of freedom of an arbitarily symmetry-constraint molecule? I heard that some knowledge like Polya theorem are requied, but I am not sure. It will be better if some reviews can be reccommended. Thank you in advance. Any suggestions will be appreciated. Best regards! ---------------------------------------------------------------- Jun Zhang (coolrainbow^-^yahoo.cn) Computational Chemistry Group No.94, Weijinlu Nankai University Tianjin, China