From schiffer@h1tw0036.hoechst.com Fri Apr 4 02:33:53 1997 Received: from backup.hoechst.com for schiffer@h1tw0036.hoechst.com by www.ccl.net (8.8.3/950822.1) id CAA05898; Fri, 4 Apr 1997 02:02:16 -0500 (EST) Received: by backup.hoechst.com (SMI-8.6/SMI-SVR4) id IAA14975; Fri, 4 Apr 1997 08:59:52 +0200 Received: from unknown(134.81.79.248) by backup via smap (V1.3) id sma014927; Fri Apr 4 08:52:24 1997 Received: from 134.81.76.36 by fra28.hiserv.de with SMTP (Microsoft Exchange Internet Mail Connector Version 4.0.994.63) id HV0NC1PN; Fri, 4 Apr 1997 08:58:42 +0200 Received: from h1tw0024 by h1tw0036 via SMTP (940816.SGI.8.6.9/940406.SGI.AUTO) id IAA01570; Fri, 4 Apr 1997 08:53:35 +0200 Message-ID: <3344A56E.41C6@h1tw0036.hoechst.com> Date: Fri, 04 Apr 1997 08:53:34 +0200 From: "Dr. Heinz Schiffer" Organization: Hoechst Corporate Research & Technology X-Mailer: Mozilla 2.0 (X11; I; IRIX 5.3 IP22) MIME-Version: 1.0 To: "M.Govender" , Computational Chemistry List Subject: Re: CCL:Temperature Calculations References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit M.Govender wrote: > > Dear Netters, > > I am interested in obtaining Rotational and Vibrational > temperature calculations on spherical top molecules. Can anyone > provide any info as to what programs are available?... > > Many Thanks > Magan Hi Magan, Look at Donald A. McQuarrie, Statistical Mechanics, Harper & Row 1976. All the relevant formulars are there. The vibrational temperature of the normal frequency nu_j is Theta_nu_j = h * nu_j / k The rotational temperatures of a general polyatomic molecule are : Theta_A = A / k Theta_B = B / k Theta_C = C / k A, B, and C are the rotational constants in Joule. Normally they are given in cm**(-1), that is as A_quer = A / ( h * c ). A, B, and C are defined as A = h**2 / ( 8 * pi**2 * I_A ) B = h**2 / ( 8 * pi**2 * I_B ) C = h**2 / ( 8 * pi**2 * I_C ) I_A, I_B, and I_C are the principle moments of inertia. You can get them by diagonalizing the moments of inertia tensor. The formalas in the McQuarrie book on page 134 are wrong : I_xy is missing a negative sign : I_xy = - sum_j .... and in the formulas for A_quer, B_quer, and C_quer the pi should be squared, see above. Ciao, Heinz -- Dr. Heinz Schiffer Phone ++49-69-305-2330 Hoechst CR&T Fax ++49-69-305-81162 Scientific Computing, G864 Email schiffer@h1tw0036.hoechst.com 65926 Frankfurt am Main schiffer@msmwia.hoechst.com