From owner-chemistry*- at -*ccl.net Sun Jan 13 10:07:00 2013 From: "Dr. Lars Goerigk lars.goerigk]*[chem.usyd.edu.au" To: CCL Subject: CCL:G: Unexpected error in G09 Rev B.01 Message-Id: <-48060-130112174310-21182-XE9JAWaPxR/RScLgsZTP2g+*+server.ccl.net> X-Original-From: "Dr. Lars Goerigk" Content-Type: multipart/alternative; boundary="------------080900000509090703050502" Date: Sun, 13 Jan 2013 09:42:42 +1100 MIME-Version: 1.0 Sent to CCL by: "Dr. Lars Goerigk" [lars.goerigk[#]chem.usyd.edu.au] This is a multi-part message in MIME format. --------------080900000509090703050502 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hi Sam and Massimo, just a comment to Sam's comment. Using CIS for DFT does make sense and several programs also allow to do that. Then one usually speaks of TDA-DFT, where TDA stands for the Tamm-Dancoff approximation. From another point of view, if you take the RPA equation (TD-HF) and evoke TDA, then the resulting equation is the CIS equation. As linear response TD-DFT is very similar to the TD-HF equations, you can do the same for TD-DFT and get TDA-DFT and I assume that is what Massimo wanted to do when he tried to evoke CIS/B3LYP. However, I am not sure whether Gaussian allows it. I know that NWCHEM and ORCA allow to do TDA-DFT. Excitation energies are very similar to those of full linear response TD-DFT, at a lower computational cost. Transition dipole moments were reported to be more effected by this approximation, however. I hope this could help. Cheers, Lars -- Dr. Lars Goerigk School of Chemistry (Building F11) The University of Sydney, NSW 2006 Australia Profile: http://www.researchgate.net/profile/Lars_Goerigk List of publications: www.researcherid.com/rid/D-3717-2009 --------------080900000509090703050502 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hi Sam and Massimo,

just a comment to Sam's comment. Using CIS for DFT does make sense and several programs also allow to do that. Then one usually speaks of TDA-DFT, where TDA stands for the Tamm-Dancoff approximation. From another point of view, if you take the RPA equation (TD-HF) and evoke TDA, then the resulting equation is the CIS equation. As linear response TD-DFT is very similar to the TD-HF equations, you can do the same for TD-DFT and get TDA-DFT and I assume that is what Massimo wanted to do when he tried to evoke CIS/B3LYP.

However, I am not sure whether Gaussian allows it. I know that NWCHEM and ORCA allow to do TDA-DFT. Excitation energies are very similar to those of full linear response TD-DFT, at a lower computational cost. Transition dipole moments were reported to be more effected by this approximation, however.

I hope this could help.

Cheers,
Lars
--
Dr. Lars Goerigk
School of Chemistry (Building F11)
The University of Sydney, NSW 2006
Australia
Profile: http://www.researchgate.net/profile/Lars_Goerigk
List of publications: www.researcherid.com/rid/D-3717-2009
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