tag:blogger.com,1999:blog-3599722177679860131.post123245182655987218..comments2024-01-03T10:01:29.738+01:00Comments on Chemical Quantum Images: HOMO-LUMO gaps and excitation energiesFelixhttp://www.blogger.com/profile/05138335803929997277noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-3599722177679860131.post-45407462986920404612018-08-31T09:37:11.301+01:002018-08-31T09:37:11.301+01:00Awesome blog and its well written to understand it...Awesome blog and its well written to understand it.<br /><a rel="nofollow">difference between homo and lumo</a><br />Douglas adamhttps://www.blogger.com/profile/08229025979804163105noreply@blogger.comtag:blogger.com,1999:blog-3599722177679860131.post-10163605870454801302015-12-04T05:22:52.201+01:002015-12-04T05:22:52.201+01:00Dear Sir I am using HOMO and LUMO energy in corros...Dear Sir I am using HOMO and LUMO energy in corrosion research. I want to know that I am getting similar pictures both for HOMO and LUMO. Then how can I explain which is site in the molecule is electron donar and which is electron acceptor from metal. Please suggest me the correct answer Anonymoushttps://www.blogger.com/profile/15285139032909588844noreply@blogger.comtag:blogger.com,1999:blog-3599722177679860131.post-13040089074909987782013-12-30T10:24:49.932+01:002013-12-30T10:24:49.932+01:00If you want to start from scratch, you would usual...If you want to start from scratch, you would usually go for something like Hückel theory, see e.g. these posts:<br />http://chemical-quantum-images.blogspot.co.at/2007/08/h-package.html<br />http://www.chemical-quantum-images.blogspot.co.at/2007/09/h-package-2.html<br /><br />This is something you can do with little effort. and it will give you HOMO-LUMO gaps that make sense when you compare them to absorption energies for example. and you can understand aromaticity<br /><br />ab-initio Hartree-Fock is much more difficult to implement because you need to compute 6-dimensional integrals as shown in the first equation of this post<br />http://chemical-quantum-images.blogspot.co.at/2013/09/density-fitting-and-tensor-hyper.htmlFelixhttps://www.blogger.com/profile/05138335803929997277noreply@blogger.comtag:blogger.com,1999:blog-3599722177679860131.post-9075780624190678322013-12-27T19:41:51.761+01:002013-12-27T19:41:51.761+01:00Thank You Sir...!!!
As I'm amateur in the fiel...Thank You Sir...!!!<br />As I'm amateur in the field,, so I want to start everything from the beginning. I want to write an in-general MATLAB code to compute HOMO/LUMO for organic molecules and polymers. As HF doesn't include e-e correlation, so does it affect calculated HOMO/LUMO energy levels?<br />Is it a feasible idea to do everything from very scratch?DEEPAKhttps://www.blogger.com/profile/03489169110092413467noreply@blogger.comtag:blogger.com,1999:blog-3599722177679860131.post-66771015135359949632013-12-27T16:30:48.694+01:002013-12-27T16:30:48.694+01:00Hi, the problem is that the HOMO and LUMO are not ...Hi, the problem is that the HOMO and LUMO are not well-defined physical quantities. They can be applied in some qualitative theories, but there is no rigiorous way to compute them, since they are method dependent<br /><br />anyway, you can download a program like GAMESS<br />http://www.msg.ameslab.gov/gamess/<br />and play around a little bit. Use a small basis set like 6-31G*. Then do HF and DFT/B3LYP computations. And compare the results to get an idea about what is happeningFelixhttps://www.blogger.com/profile/05138335803929997277noreply@blogger.comtag:blogger.com,1999:blog-3599722177679860131.post-48653789640810239352013-12-27T14:20:56.365+01:002013-12-27T14:20:56.365+01:00Hello Sir,
I am interested in computing HOMO and L...Hello Sir,<br />I am interested in computing HOMO and LUMO energy levels from methods like DFT and HF.<br />As you are an expert in this field, so I need a suggestion. Which of these two method will be best suited for this computation?<br />I want to start everything from the beginning.DEEPAKhttps://www.blogger.com/profile/03489169110092413467noreply@blogger.com