From owner-chemistry@ccl.net Sat May 12 00:54:00 2012 From: "Matthew Reish Reishme04|-|gmail.com" To: CCL Subject: CCL: TD-DFT MO contributions Message-Id: <-46888-120512005248-17875-xzEfPCW7MTcM+DUg4CcWCg*o*server.ccl.net> X-Original-From: "Matthew Reish" Date: Sat, 12 May 2012 00:52:45 -0400 Sent to CCL by: "Matthew Reish" [Reishme04**gmail.com] In the calculation of TD-DFT (B3LYP-6-31G(d)) excitations of a 12 unit carbazole oligomer I find that TD-DFT describes the excitation as being a combination of many ground and excited state orbitals (5 homos and 5 lumos). Can anyone help me by explaining how a 1-electron excitation can involve several 1-electron orbitals. Also, does this indicate that the physicality of the excited state orbital will be as diffuse as that of the combination of orbitals or is the excited electron still limited to a single orbital. Any insight or suggested readings that address this topic would be welcome. Thanks for your help, Matthew Reish University of Otago Dunedin New Zealand From owner-chemistry@ccl.net Sat May 12 01:29:01 2012 From: "Eli Lam elizabeth.shlam:-:gmail.com" To: CCL Subject: CCL: equilibrium solvation TDDFT and non-equilibrium solvation Message-Id: <-46889-120512005654-30201-2hQZ+RF71l3bthYGcDRFJA!^!server.ccl.net> X-Original-From: "Eli Lam" Date: Sat, 12 May 2012 00:56:51 -0400 Sent to CCL by: "Eli Lam" [elizabeth.shlam],[gmail.com] Hi all, I've learnt that there are two methods in TDDFT, the equilibrium and the non- equilibrium. The default in g09 is non-equilibrium. I would like to ask if I'm to calculate the excited state, which method is more preferred? And how are these two methods different from each other? Thank you very much! Eli From owner-chemistry@ccl.net Sat May 12 15:25:00 2012 From: "John McKelvey jmmckel%%gmail.com" To: CCL Subject: CCL: IR Spectra (Frequency Calculation) Message-Id: <-46890-120512115053-11783-pV/M2LmPjW+uUIdnFgtE5Q\a/server.ccl.net> X-Original-From: John McKelvey Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=ISO-8859-1 Date: Sat, 12 May 2012 11:50:45 -0400 MIME-Version: 1.0 Sent to CCL by: John McKelvey [jmmckel*gmail.com] Thought... Without external constraints surely a molecule will still vibrate freely on going from State A to State B. How, then, does one characterize the vibrations along the path from State A to State B? I think the original question is still worth answering if possible. I once had to deal with a similar type conundrum related to how structural changes would affect the dipole moments of charged systems... John McKelvey On Fri, May 11, 2012 at 6:05 AM, Dillen, Jan jlmda/sun.ac.za JLMDa/sun.ac.za wrote: > > Sent to CCL by: "Dillen, Jan [jlmd:-:sun.ac.za]" > Hi Joe > > I may read too much in your question but if you intend to calculate "frequencies" for a conformation that is not a stationary point on your energy surface, the answer is: NO. > > Of course you can ask the computer program to do it, but the numbers are not vibrational frequencies because the eigenvalues of a mass-weighted hessian matrix are only related to normal modes (aka frequencies) if the gradient of the energy is zero, e.g. at a energy minimum of maximum. > > See the classic, but still relevant book by Wilson, Decius & Cross. > > Jan > > -----Original Message----- >> From: owner-chemistry+jlmd==sun.ac.za!=!ccl.net [mailto:owner-chemistry+jlmd==sun.ac.za!=!ccl.net] On Behalf Of Joe Golab joseph.golab .. ineos.com > Sent: 09 May 2012 17:52 > To: Dillen, Jan > Subject: CCL: IR Spectra (Frequency Calculation) > > > Sent to CCL by: "Joe  Golab" [joseph.golab(-)ineos.com] CCL Members: > > We would like to study the IR spectrum of a molecule as a function of its conformation. > > Obviously, a strictly theoretical treatment can only predict one conformer's spectrum, i.e. the lowest energy one. > > But what if the environment around a molecule prevented it from existing in its "lowest energy" (geometry optimized) configuration? > > We cannot take the environment into account, i.e. use the environment to "force" conformations for the frequency calculation. > > So, is it possible to study the IR spectrum of a molecule as a function of its conformation? > > Thanks for your consideration. > > Joe > ___________________________ > Joseph T. Golab, PhD > Molecular Modeling & Simulation Scientist Senior Research Scientist INEOS Technologies, Nitriles R&D > Phone: +1 (630) 420-5063 > Cell:  +1 (630) 336-0063 > Email: Joseph.Golab_at_ineos.comhttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp://www.ccl.net/spammers.txtE-pos vrywaringsklousule > > Hierdie e-pos mag vertroulike inligting bevat en mag regtens geprivilegeerd wees en is slegs bedoel vir die persoon aan wie dit geadresseer is. Indien u nie die bedoelde ontvanger is nie, word u hiermee in kennis gestel dat u hierdie dokument geensins mag gebruik, versprei of kopieer nie. Stel ook asseblief die sender onmiddellik per telefoon in kennis en vee die e-pos uit. Die Universiteit aanvaar nie aanspreeklikheid vir enige skade, verlies of uitgawe wat voortspruit uit hierdie e-pos en/of die oopmaak van enige lêers aangeheg by hierdie e-pos nie. > > E-mail disclaimer > > This e-mail may contain confidential information and may be legally privileged and is intended only for the person to whom it is addressed. If you are not the intended recipient, you are notified that you may not use, distribute or copy this document in any manner whatsoever. Kindly also notify the sender immediately by telephone, and delete the e-mail. The University does not accept liability for any damage, loss or expense arising from this e-mail and/or accessing any files attached to this e-mail.>      http://www.ccl.net/cgi-bin/ccl/send_ccl_message>      http://www.ccl.net/cgi-bin/ccl/send_ccl_message>      http://www.ccl.net/chemistry/sub_unsub.shtml>      http://www.ccl.net/spammers.txt> > -- John McKelvey 10819 Middleford Pl Ft Wayne, IN 46818 260-489-2160 jmmckel::gmail.com From owner-chemistry@ccl.net Sat May 12 16:00:00 2012 From: "Benjamin Stein benjamin.w.stein{:}gmail.com" To: CCL Subject: CCL: TD-DFT MO contributions Message-Id: <-46891-120512124735-30547-pT6mV+gSJBoRYgYIYPaYxA^server.ccl.net> X-Original-From: Benjamin Stein Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=us-ascii Date: Sat, 12 May 2012 10:47:23 -0600 Mime-Version: 1.0 (Apple Message framework v1278) Sent to CCL by: Benjamin Stein [benjamin.w.stein _ gmail.com] Hi Matthew, Good questions! Interpreting TD-DFT results is tricky, but can be quite fruitful. I've had a bit of trouble understanding some of the concepts myself, so hopefully I can share a little. I'm sure there are others here (far more experienced than me!) who can chime in as well. Remember that transitions are between _states_ and not orbitals (which are almost always optimized for the ground state) and so an excited state may differ from the ground state in a way which cannot be described by a single 1-electron promotion. In your output you'll see where the different contributions are weighted by their CI coefficient. Many different techniques have been developed to interpret CI-S results, since looking at just the 1-electron contributions can be quite confusing. Here is a couple of papers which you might like: Dreuw, A. and Head-Gordon, M. Chemical Reviews. 2005, 105, 4009-4037. Head-Gordon, M.; Grana, A. M.; Maurice, D.; and White, C. A. J. Phys. Chem. 1995, 99, 14261-14270. Martin, R. L. J Chem Phys. 2003, 118, 4775-4777. Neese, F. Coordination Chemistry Reviews. 2009, 253, 526 - 563. For the other part of your question, I think that your confusion may be that you are thinking of the excitation as involving only one particular electron. It is probably a bit more rigorous to think of it as involving a change in electron density (which is an observable, unlike orbitals) and so can involve many orbitals. As to the diffuse character of the excited state, looking at things like the electron density difference, nature of the donor and acceptor orbitals, etc can help determine that. Good luck! -Ben Benjamin Stein University of New Mexico On May 11, 2012, at 10:52 PM, Matthew Reish Reishme04|-|gmail.com wrote: > > Sent to CCL by: "Matthew Reish" [Reishme04**gmail.com] > In the calculation of TD-DFT (B3LYP-6-31G(d)) excitations of a 12 unit > carbazole oligomer I find that TD-DFT describes the excitation as being a > combination of many ground and excited state orbitals (5 homos and 5 lumos). > Can anyone help me by explaining how a 1-electron excitation can involve > several 1-electron orbitals. Also, does this indicate that the physicality of > the excited state orbital will be as diffuse as that of the combination of > orbitals or is the excited electron still limited to a single orbital. Any > insight or suggested readings that address this topic would be welcome. > > Thanks for your help, > > Matthew Reish > University of Otago > Dunedin New Zealand> >