Re: [Wien] Adding excitonic effects
Dear Xavier, Thank you very much for your quick and detailed reply. I am calculating the valance optical properties, where the hole is positioned in the valance states; JDOS, Energy loss function etc. Thanks - Original Message - From: Xavier Rocquefelte xavier.rocquefe...@univ-rennes1.fr To: A Mailing list for WIEN2k users wien@zeus.theochem.tuwien.ac.at Sent: Saturday, May 16, 2015 11:58:08 AM Subject: Re: [Wien] Adding excitonic effects To properly describe an exciton, which is a two-particle entitie, you need a two-particle theory at least. DFT is a one particle theory, thus it is not suited to properly describe excitonic effects. For solids you must use the Bethe Salpeter Equation (BSE) which is implemented in other codes and very expensive in terms of computational time and memory. Another strategy is to mimick the effect of the exciton on the optical properties using DFT and a corehole approach. This last strategy is pragmatic and not exact, but it allows to deals with this 2-particle problem using a one-particle approach in a mean-field manner. Usually, a half corehole is used. It corresponds to the Slater transition state and it gives nice results in general. What kind of transtions are your doing? Does it implies core states? If yes you can easily remove half an electron in the file case.inc. If the transition is from valence states, the problem is more tricky to solve. Best Regards Xavier Dileep Krishnan dil...@jncasr.ac.in a écrit : Hi Users and Developers, I was calculating optical properties by OPTIC program. How can I add excitonic effects into the calculation? -- Dileep Krishnan, Int. Ph. D Student, International Centre for Materials Science (ICMS), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore-560064, INDIA. ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html -- Dileep Krishnan, Int. Ph. D Student, International Centre for Materials Science (ICMS), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore-560064, INDIA. ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
Re: [Wien] Adding excitonic effects
Here is a document that can be usefull in which Peter discussed briefly valence hole for emission spectra: http://www.wien2k.at/reg_user/textbooks/WIEN2k_lecture-notes_2011/Blaha_xas_eels.pdf Regards Xavier Dileep Krishnan dil...@jncasr.ac.in a écrit : Dear Xavier, Thank you very much for your quick and detailed reply. I am calculating the valance optical properties, where the hole is positioned in the valance states; JDOS, Energy loss function etc. Thanks - Original Message - From: Xavier Rocquefelte xavier.rocquefe...@univ-rennes1.fr To: A Mailing list for WIEN2k users wien@zeus.theochem.tuwien.ac.at Sent: Saturday, May 16, 2015 11:58:08 AM Subject: Re: [Wien] Adding excitonic effects To properly describe an exciton, which is a two-particle entitie, you need a two-particle theory at least. DFT is a one particle theory, thus it is not suited to properly describe excitonic effects. For solids you must use the Bethe Salpeter Equation (BSE) which is implemented in other codes and very expensive in terms of computational time and memory. Another strategy is to mimick the effect of the exciton on the optical properties using DFT and a corehole approach. This last strategy is pragmatic and not exact, but it allows to deals with this 2-particle problem using a one-particle approach in a mean-field manner. Usually, a half corehole is used. It corresponds to the Slater transition state and it gives nice results in general. What kind of transtions are your doing? Does it implies core states? If yes you can easily remove half an electron in the file case.inc. If the transition is from valence states, the problem is more tricky to solve. Best Regards Xavier Dileep Krishnan dil...@jncasr.ac.in a écrit : Hi Users and Developers, I was calculating optical properties by OPTIC program. How can I add excitonic effects into the calculation? -- Dileep Krishnan, Int. Ph. D Student, International Centre for Materials Science (ICMS), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore-560064, INDIA. ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html -- Dileep Krishnan, Int. Ph. D Student, International Centre for Materials Science (ICMS), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore-560064, INDIA. ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
Re: [Wien] Adding excitonic effects
FYI, there is a separate BSE code for WIEN2k called BSE@WIEN2k. It seems to require a cluster with hundreds of cores and a large amount of memory as described on slide 23 in the document at: http://www.wien2k.at/reg_user/textbooks/WIEN2k_lecture-notes_2013/DFT_advanced.pdf It cannot be downloadable from Dr. C. Ambrosch-Draxl's old website anymore as it no longer exists. However, you should be able to still read about it on wayback: https://web.archive.org/web/20120415092421/http://amadm.unileoben.ac.at/codes_wien2k.html If your interested in it, I think you can try requesting it from Dr. R. Laskowski: http://www.mail-archive.com/wien%40zeus.theochem.tuwien.ac.at/msg03642.html On 5/16/2015 12:28 AM, Xavier Rocquefelte wrote: To properly describe an exciton, which is a two-particle entitie, you need a two-particle theory at least. DFT is a one particle theory, thus it is not suited to properly describe excitonic effects. For solids you must use the Bethe Salpeter Equation (BSE) which is implemented in other codes and very expensive in terms of computational time and memory. Another strategy is to mimick the effect of the exciton on the optical properties using DFT and a corehole approach. This last strategy is pragmatic and not exact, but it allows to deals with this 2-particle problem using a one-particle approach in a mean-field manner. Usually, a half corehole is used. It corresponds to the Slater transition state and it gives nice results in general. What kind of transtions are your doing? Does it implies core states? If yes you can easily remove half an electron in the file case.inc. If the transition is from valence states, the problem is more tricky to solve. Best Regards Xavier Dileep Krishnan dil...@jncasr.ac.in a écrit : Hi Users and Developers, I was calculating optical properties by OPTIC program. How can I add excitonic effects into the calculation? -- Dileep Krishnan, Int. Ph. D Student, International Centre for Materials Science (ICMS), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore-560064, INDIA. ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
Re: [Wien] Adding excitonic effects
To properly describe an exciton, which is a two-particle entitie, you need a two-particle theory at least. DFT is a one particle theory, thus it is not suited to properly describe excitonic effects. For solids you must use the Bethe Salpeter Equation (BSE) which is implemented in other codes and very expensive in terms of computational time and memory. Another strategy is to mimick the effect of the exciton on the optical properties using DFT and a corehole approach. This last strategy is pragmatic and not exact, but it allows to deals with this 2-particle problem using a one-particle approach in a mean-field manner. Usually, a half corehole is used. It corresponds to the Slater transition state and it gives nice results in general. What kind of transtions are your doing? Does it implies core states? If yes you can easily remove half an electron in the file case.inc. If the transition is from valence states, the problem is more tricky to solve. Best Regards Xavier Dileep Krishnan dil...@jncasr.ac.in a écrit : Hi Users and Developers, I was calculating optical properties by OPTIC program. How can I add excitonic effects into the calculation? -- Dileep Krishnan, Int. Ph. D Student, International Centre for Materials Science (ICMS), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore-560064, INDIA. ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
[Wien] Adding excitonic effects
Hi Users and Developers, I was calculating optical properties by OPTIC program. How can I add excitonic effects into the calculation? -- Dileep Krishnan, Int. Ph. D Student, International Centre for Materials Science (ICMS), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore-560064, INDIA. ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
