[Wien] Comparison between ab inito calculation and "measurement" result
Dear group, As an engineering researcher with great lack in understanding the ab initio calculations, I have basically believed that the first-principle calculation results demonatrate rather "ideal" values presumably obtained at "0 K" and they need to be adjusted by proper mathematical models formulated as a function of temperature for reachiing the more practical values at non-0 K values. However, in many pieces of literature, they are trying to compare the ab initio calculation results and the measurement results at non-0 K, particularly at room temperature. I'm wondering what sort of foundation is required for believing that the simulation results can be treated as those obtained at 300 K. In other words, what models or equations can be adopted for taking the exact band structures and related parameters (Eg, effective mass, etc.) in hand in performing the first-principle simulations? It will be appreciated if you fix my fault and share some wisdom. Many thanks. - Sincerely, Seongjae. ___ 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] Control of very small fraction of atoms in alloy
Dear Lyudmila, Thank you for your e-mail with kind explanation. Sorry for having forgotten to answer earlier but it seems that the task is going well now on the belief that the first guess on simulation direction is right by your supporting advice , and with the tips you provided. We made a large supercell first and then put one of two atoms forcefully and manually, which looks a possible solution for now. So far so good. :-) I'll keep the number of parameters in mind so that they are not making too heavy loads on the simulation computer. Thank you so much and good luck with your works! - Sincerely, Seongjae. - Original Message - From: Lyudmila Dobysheva lyuk...@mail.ru To: A Mailing list for WIEN2k users wien@zeus.theochem.tuwien.ac.at Date: Thu, 13 Aug 2015 18:09:04 +0900 (GMT) subject: Re: [Wien] Control of very small fraction of atoms in alloy 13.08.2015 06:46, Seongjae Cho пишет: So, a simple idea that struck me was it would be really good if there might be a way to put extrinsic atoms one by one into that already made supper cell having 100 or so basis atoms. Yes, this is a right way. With large supercells you should check, with a higher attention, a convergence of the calculation over calculational parameters (Rkmax, N k-points), over the values you want to study. Making calc parameters higher increases calculational time, so you should find a compromise between accuracy and the time. Best way is, first, to make a calcuation with lower parameters, then to increase them, and so forth. The accuracy, that you need to chose, depends strongly on your task. There is a huge set of papers made under WIEN2k http://www.wien2k.at/papers/index.html You can find there studies that may be compared with your task. Best wishes Lyudmila Dobysheva -- Phys.-Techn. Institute of Ural Br. of Russian Ac. of Sci. 426001 Izhevsk, ul.Kirova 132 RUSSIA -- Tel.:7(3412) 432045(office), 722529(Fax) E-mail: l...@ftiudm.ru, lyuk...@mail.ru (office) lyuk...@gmail.com (home) Skype: lyuka17 (home), lyuka18 (office) http://ftiudm.ru/content/view/25/103/lang,english/ -- ___ 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] Control of very small fraction of atoms in alloy
Dear users, As an electronic device researcher, I started to run Wien2k recently. What I'm interested in is to see what really happens to the electronic structures (bandgap and extraction of carrier mobility from it, etc.) in an alloy when the fraction of one of the comprising atoms is very slightly changed, by like 1 % or below step. Maybe we can think about Si1-xGex for x = 0.015, 0.02, 0.025, etc, as an example. If I make an approach through the supper-lattice method, i.e., if I first replace one of the A atoms by a B atom and send the unit cell to many directions, it would give a very large portion itself and very large portion spacing as well. Replacement of even only 1 or 2 atoms out of 8 atoms in the diamond structure, for example, would make 12.5% and 25% atomic fraction and fraction changes. So, a simple idea that struck me was it would be really good if there might be a way to put extrinsic atoms one by one into that already made supper cell having 100 or so basis atoms. I'm wondering if this sounds good and if it is a feasible method that has been accepted in running Wien2k. But, it's an idea yet even though it is a right way. So, it will be greatly appreciated if you share some know-hows to make this happen. Thank you for your kind helps and communications in advance. - Sincerely, Seongjae. I'm a novice in this area but having a real fun with this. Thanks for the supporing group and all the other users. ___ 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
