From chemistry-request@server.ccl.net Thu Oct 4 07:54:19 2001 Received: from century.fen.bilkent.edu.tr ([139.179.97.100]) by server.ccl.net (8.11.6/8.11.0) with ESMTP id f94BsGB22204 for ; Thu, 4 Oct 2001 07:54:17 -0400 Received: from pinar (pinar [139.179.97.99]) by century.fen.bilkent.edu.tr (8.9.1/8.9.1) with ESMTP id OAA09242 for ; Thu, 4 Oct 2001 14:51:59 +0300 (EET DST) Date: Thu, 4 Oct 2001 15:03:19 +0300 (EET DST) From: Ulrike Salzner X-Sender: salzner@pinar To: ccl Subject: size of s,p,d orbitals Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Dear Collegues, until 1 hour ago, I firmly believed that p-orbitals are larger than s- orbitals for atoms that are in the same row of the periodic table. Only for the second row the sizes were about same. This conviction is mainly due to a paper by Werner Kutzelnigg, Angew. Chem. 1984, 96, 262-286. I further believed that s electrons are attracted stronger by the nuclei because they have no node at the position of the nucleus and that the similar size of s- and p-orbitals in the second row is due to the lack of 1p orbitals and therefore cancellation of two effects: less attraction of p electrons due to the node and lack of repulsion between 2p and a lower shell p-orbital. This is also what I kept telling our first year students. Today a collegue approached me who teaches inorganic chemistry to our third year students. She told me that she was surprized that the students did not know that the order according to decreasing size is s > p > d within the same row. After admitting that this was to be blamed on me, she showed me the Inorganic Chemistry textbook by Huhee. There are plots of radial distribution times r square, clearly indicating that the maximum shifts to smaller values from s to p to d. Huhee quotes Herberg's "Atomic Spectra and Atomic Structure" from 1944. In Kutzelniggs article the average distance of electrons from the nucleus was used not radial distribution times r square. The question now is: Do the two ways to determine the size of the orbitals lead to different conclusions? Is there a mistake somewhere? Is there newer information? Which orbitals are bigger? What is best method to determine the size to explain bonding, hybridization, or lack thereof and so on? Thanks in advance for suggestions, Ulrike Salzner =================================================================== Dr. Ulrike Salzner Associate Professor Department of Chemistry Tel.: (312) 290-2122 Bilkent University Fax.: (312) 266-5097 06533 Bilkent, Ankara e-mail: salzner@fen.bilkent.edu.tr Turkey ==================================================================== From chemistry-request@server.ccl.net Thu Oct 4 05:58:45 2001 Received: from mel.ruc.dk ([130.225.220.27]) by server.ccl.net (8.11.6/8.11.0) with ESMTP id f949wiB19717 for ; Thu, 4 Oct 2001 05:58:44 -0400 Received: from smtprelay.ruc.dk (smtprelay.ruc.dk [130.225.220.22]) by mel.ruc.dk (8.9.3/8.9.1) with ESMTP id LAA19484; Thu, 4 Oct 2001 11:58:43 +0200 (MET DST) Received: from virgil.ruc.dk (virgil.ruc.dk [130.225.220.110]) by smtprelay.ruc.dk (8.9.3+Sun/8.9.3) with ESMTP id LAA06806; Thu, 4 Oct 2001 11:34:43 +0200 (MEST) Received: from VIRGIL/SpoolDir by virgil.ruc.dk (Mercury 1.47); 4 Oct 01 11:58:43 +0100 Received: from SpoolDir by VIRGIL (Mercury 1.47); 4 Oct 01 11:58:38 +0100 From: "Jens Spanget-Larsen" Organization: Roskilde Universitetscenter To: Ali Rashid Date: Thu, 4 Oct 2001 11:58:24 +0100 Subject: CCL:Linear dichroism. CC: chemistry@ccl.net X-Confirm-Reading-To: "Jens Spanget-Larsen" X-pmrqc: 1 Priority: normal X-mailer: Pegasus Mail for Windows (v2.23) Message-ID: Ali Rashid: > Hi, I was wandering if anyone knows of a way to simulate the > absorption spectra of a system. What i am interested in is, starting > from a model of a molecules or molecules packed in a certain way, > can i then calculate things like the dichroic ratio and the linear > dichroism? Thank you in advance. -- Dear Ali, In principle, transition energies, oscillator strengths and transition moment directions of molecular optical transitions can be predicted by quantum chemical calculations (the presence of molecular symmetry elements may be of great help in this task). It is then possible to predict the dichroic ratio and the linear dichroism of an assembly of molecules "packed in a certain way", since the resulting absorption probability is proportional to the cosine-squared of the angle between the individual moment directions and the electric vector of the linearly polarized light. See the volume by Michl and Thulstrup: J. Michl, E. W. Thulstrup: "Spectroscopy with Polarized Light. Solute Alignment by Photoselection, in Liquid Crystals, Polymers, and Membranes", VCH Publishers 1986, 1995 (ISBN 1-56081-910-3). Yours, Jens >--< =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- JENS SPANGET-LARSEN Office: +45 4674 2710 Department of Chemistry Fax: +45 4674 3011 Roskilde University (RUC) Cell-Phone: +45 2320 6246 P.O.Box 260 E-Mail: JSL@virgil.ruc.dk DK-4000 Roskilde, Denmark http://virgil.ruc.dk/~jsl =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- From chemistry-request@server.ccl.net Thu Oct 4 12:27:04 2001 Received: from soul.helsinki.fi ([128.214.3.1]) by server.ccl.net (8.11.6/8.11.0) with ESMTP id f94GR4B28560 for ; Thu, 4 Oct 2001 12:27:04 -0400 Received: from localhost (mpjohans@localhost) by soul.helsinki.fi (8.9.3/8.9.3) with ESMTP id TAA19080; Thu, 4 Oct 2001 19:26:34 +0300 (EET DST) X-Authentication-Warning: soul.helsinki.fi: mpjohans owned process doing -bs Date: Thu, 4 Oct 2001 19:26:33 +0300 (EET DST) From: Mikael Johansson X-Sender: To: Ulrike Salzner cc: ccl Subject: Re: CCL:size of s,p,d orbitals In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Hello Ulrike and All! On Thu, 4 Oct 2001, Ulrike Salzner wrote: > until 1 hour ago, I firmly believed that p-orbitals are larger than s- > orbitals for atoms that are in the same row of the periodic table. Only [...] > third year students. She told me that she was surprized that the students > did not know that the order according to decreasing size is s > p > d [...] > The question now is: Do the two ways to determine the size of the orbitals > lead to different conclusions? Is there a mistake somewhere? Is there > newer information? Which orbitals are bigger? What is best method to > determine the size to explain bonding, hybridization, or lack thereof and > so on? This was an interesting question, succeeding in diverting me from things I should be doing :-) Without taking a stand on what method is the "best" I made a quick calculation on the argon-atom and compared the "sizes" of the 2s/2p and 3s/3p orbitals. Below is reported the radius of a spherical boundary around the atom which contains 90% resp. 95% of the electron density of the orbital in question: (the calculation was made on B3LYP/TZVP level, for no specific reason) 90% 95% 2s 0.65 0.74 a.u. 2p 0.63 0.72 3s 2.14 2.44 3p 2.64 3.06 So according to the above the 2s/2p-orbitals are about as big, whereas the 3s is smaller than the 3p. Other comments on the subject would be very welcome! Have a nice day, Mikael Johansson University of Helsinki Department of Chemistry mikael.johansson@helsinki.fi Phone: +358-9-191 50185 FAX : +358-9-191 50169 From chemistry-request@server.ccl.net Thu Oct 4 14:25:43 2001 Received: from umc-mail01.missouri.edu ([128.206.10.216]) by server.ccl.net (8.11.6/8.11.0) with ESMTP id f94IPhB31236 for ; Thu, 4 Oct 2001 14:25:43 -0400 Received: from [128.206.98.1] (mu-098001.dhcp.missouri.edu [128.206.98.1]) by umc-mail01.missouri.edu with SMTP (Microsoft Exchange Internet Mail Service Version 5.5.2653.13) id 4GNNJF72; Thu, 4 Oct 2001 13:25:43 -0500 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Sender: HarrisR@pop.email.missouri.edu Message-Id: In-Reply-To: Date: Thu, 4 Oct 2001 13:39:13 -0500 To: Ulrike Salzner , ccl From: "Robert E. Harris" Subject: Re: CCL:size of s,p,d orbitals The discussion given in Chs. 8 and 9 of Slater's Quantum Theory of Atomic Structure, v. I still seems to me one of the clearest on the subject. John C. Slater, Quantum Theory of Atomic Structure, v. I, McGraw Hill, New York, Toronto, London, 1960. REH >Dear Collegues, >until 1 hour ago, I firmly believed that p-orbitals are larger than s- >orbitals for atoms that are in the same row of the periodic table. Only >for the second row the sizes were about same. This conviction is mainly >due to a paper by Werner Kutzelnigg, Angew. Chem. 1984, 96, 262-286. I >further believed that s electrons are attracted stronger by the nuclei >because they have no node at the position of the nucleus and that the >similar size of s- and p-orbitals in the second row is due to the lack of >1p orbitals and therefore cancellation of two effects: less attraction of >p electrons due to the node and lack of repulsion between 2p and a lower >shell p-orbital. This is also what I kept telling our first year students. > >Today a collegue approached me who teaches inorganic chemistry to our >third year students. She told me that she was surprized that the students >did not know that the order according to decreasing size is s > p > d >within the same row. After admitting that this was to be blamed on me, she >showed me the Inorganic Chemistry textbook by Huhee. There are plots of >radial distribution times r square, clearly indicating that the maximum >shifts to smaller values from s to p to d. Huhee quotes Herberg's "Atomic >Spectra and Atomic Structure" from 1944. In Kutzelniggs article the >average distance of electrons from the nucleus was used not radial >distribution times r square. > >The question now is: Do the two ways to determine the size of the orbitals >lead to different conclusions? Is there a mistake somewhere? Is there >newer information? Which orbitals are bigger? What is best method to >determine the size to explain bonding, hybridization, or lack thereof and >so on? > >Thanks in advance for suggestions, >Ulrike Salzner >=================================================================== > >Dr. Ulrike Salzner >Associate Professor >Department of Chemistry Tel.: (312) 290-2122 >Bilkent University Fax.: (312) 266-5097 >06533 Bilkent, Ankara e-mail: salzner@fen.bilkent.edu.tr >Turkey > Robert E. Harris Phone: 573-882-3274. Fax: 573-882-2754 Department of Chemistry, University of Missouri-Columbia Columbia, Missouri, USA 65211 From chemistry-request@server.ccl.net Thu Oct 4 14:25:50 2001 Received: from physics.lsu.edu ([130.39.182.96]) by server.ccl.net (8.11.6/8.11.0) with ESMTP id f94IPoB31254 for ; Thu, 4 Oct 2001 14:25:50 -0400 Received: from localhost (vani@localhost) by physics.lsu.edu (8.9.2/8.9.2) with ESMTP id NAA29120 for ; Thu, 4 Oct 2001 13:23:26 -0500 (CDT) Date: Thu, 4 Oct 2001 13:23:26 -0500 (CDT) From: Vemparala Satyavani To: chemistry@ccl.net Subject: Coulomb forces in TIP4 model of water Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Iam want ti use TIP4 model of water in my simulation. the question is: as a result of moving the charge center from oxygen to another charge center M, when the forecs are computed( by ewald method), i get the force on that charge center, do i translate that force onto oxygen atom? or to be more clear, in TIP4 model of water does oxygen atom of water feels any force due to Coulomb(lets say Coulomb between polymer and water molecules..will the oxygen of water feel any force due to coulomb from polymer atom? Thanks vani From chemistry-request@server.ccl.net Thu Oct 4 21:17:16 2001 Received: from ultra.chem.ucsb.edu ([128.111.114.119]) by server.ccl.net (8.11.6/8.11.0) with ESMTP id f951HFB09613 for ; Thu, 4 Oct 2001 21:17:16 -0400 Received: from localhost (bushnell@localhost) by ultra.chem.ucsb.edu (8.9.3+Sun/8.9.1) with ESMTP id SAA07975; Thu, 4 Oct 2001 18:17:06 -0700 (PDT) Date: Thu, 4 Oct 2001 18:17:06 -0700 (PDT) From: John Bushnell To: Ulrike Salzner cc: ccl Subject: Re: CCL:size of s,p,d orbitals In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Regarding the argument about "the lack of repulsion between the 2p orbital and a lower shell p-orbital", I would think that this would not be an issue. If there was such a thing as a "1p" orbital, it would be spherically symmetric when filled. Thus I wouldn't expect any inherently p-specific repulsion to such a filled subshell, if it existed. That is, the s orbital would also experience such a "lack of repulsion" :-) - John bushnell@chem.ucsb.edu On Thu, 4 Oct 2001, Ulrike Salzner wrote: > Dear Collegues, > until 1 hour ago, I firmly believed that p-orbitals are larger than s- > orbitals for atoms that are in the same row of the periodic table. Only > for the second row the sizes were about same. This conviction is mainly > due to a paper by Werner Kutzelnigg, Angew. Chem. 1984, 96, 262-286. I > further believed that s electrons are attracted stronger by the nuclei > because they have no node at the position of the nucleus and that the > similar size of s- and p-orbitals in the second row is due to the lack of > 1p orbitals and therefore cancellation of two effects: less attraction of > p electrons due to the node and lack of repulsion between 2p and a lower > shell p-orbital. This is also what I kept telling our first year students. > > Today a collegue approached me who teaches inorganic chemistry to our > third year students. She told me that she was surprized that the students > did not know that the order according to decreasing size is s > p > d > within the same row. After admitting that this was to be blamed on me, she > showed me the Inorganic Chemistry textbook by Huhee. There are plots of > radial distribution times r square, clearly indicating that the maximum > shifts to smaller values from s to p to d. Huhee quotes Herberg's "Atomic > Spectra and Atomic Structure" from 1944. In Kutzelniggs article the > average distance of electrons from the nucleus was used not radial > distribution times r square. > > The question now is: Do the two ways to determine the size of the orbitals > lead to different conclusions? Is there a mistake somewhere? Is there > newer information? Which orbitals are bigger? What is best method to > determine the size to explain bonding, hybridization, or lack thereof and > so on? > > Thanks in advance for suggestions, > Ulrike Salzner > =================================================================== > > Dr. Ulrike Salzner > Associate Professor > Department of Chemistry Tel.: (312) 290-2122 > Bilkent University Fax.: (312) 266-5097 > 06533 Bilkent, Ankara e-mail: salzner@fen.bilkent.edu.tr > Turkey > > ==================================================================== > > > -= This is automatically added to each message by mailing script =- > CHEMISTRY@ccl.net -- To Everybody | CHEMISTRY-REQUEST@ccl.net -- To Admins > MAILSERV@ccl.net -- HELP CHEMISTRY or HELP SEARCH > CHEMISTRY-SEARCH@ccl.net -- archive search | Gopher: gopher.ccl.net 70 > Ftp: ftp.ccl.net | WWW: http://www.ccl.net/chemistry/ | Jan: jkl@ccl.net > > > > > From chemistry-request@server.ccl.net Thu Oct 4 22:09:50 2001 Received: from baton.phys.lsu.edu ([130.39.182.71]) by server.ccl.net (8.11.6/8.11.0) with ESMTP id f9529oB11498 for ; Thu, 4 Oct 2001 22:09:50 -0400 Received: (from vani@localhost) by baton.phys.lsu.edu (8.9.2/8.9.2) id VAA25508; Thu, 4 Oct 2001 21:03:53 -0500 (CDT) Date: Thu, 4 Oct 2001 21:03:53 -0500 (CDT) From: Vemparala Satyavani To: chemistry@ccl.net Subject: coulomb force contribution to oxygen atom in TIP4 model Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII thanks for some replies i got, but the problem is i cannot go for any prewritten software at this stage of my code, so i need to code this myself. Iam forwarding the question again, can anyone give me pointers as to how to go about distributing coulomb force felt by the artificial charge center to the 'oxygen' and 'hydrogen' atoms of hydrogen. and also should the bonds(OH,OH,OM,MH,MH), all the six of them be held rigid? as a result of moving the charge center from oxygen to another charge center M, when the forces are computed( by ewald method), i get the force on that charge center, do i translate that force onto oxygen atom? or to be more clear, in TIP4 model of water does oxygen atom of water feels any force due to Coulomb(lets say Coulomb between polymer and water molecules..will the oxygen of water feel any force due to coulomb from polymer atom? Thanks vani