[Wien] supercell structure under pressure
Dear WIEN2k users: Recently I'm calculating the f-electron material under pressure with LDA+U. There are different results between with normal structure file and with supercell structure file. The result of normal structure file with symmetry under pressure is metal. But the supercell structure under pressure result is insulator. The result of spuercell structure file in atmospheric pressure is metal. In my opinion the pressure drive the material to the metal state. Can anybody tell me what the problem is? Thank you in advance. shi kong __ Information from ESET Smart Security, version of virus signature database 4821 (20100130) __ The message was checked by ESET Smart Security. http://www.eset.com -- next part -- An HTML attachment was scrubbed... URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20100131/ec27e52a/attachment.htm
[Wien] more than one slab calculation
Dear Wien2k users, We can do surface calculation by creating one slab separated from the rest of the supercell. My question is can we create more than one slab in a single direction in Wien2k? We need slab calculation in which few slabs remain separated along say z direction. Thank you in advance... Shamik Chakrabarti Research Scholar IIT Kharagpur INDIA -- next part -- An HTML attachment was scrubbed... URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20100131/fd4f7dd9/attachment.htm
[Wien] supercell structure under pressure
Dear Shi Kong, We have very few data to answer properly to your question. What are the available experimental data and more specifically: 1/ Do you have the atomic structure (cell param. and atomic positions) for different pressures or only cell parameters variation with pressure? 2/ In the normal structure how many equivalent sites do you have for the f-element? 1 or more? If you have one equivalent position for the f-element in the normal structure, then in the supercell you have many inequivalent sites for the f-element. In other words, during the calculation of the small cell you can easily converged to metal state because all f-atoms are equivalently occupied. In contrast, in the supercell you allow to have different electronic configurations for the f-atoms in inequivalent sites. In such situation, you should be very careful during the SCF convergency, because you could have charge oscillations due to the alternative occupation of the inequivalent f-atoms. In addition, you should need to help the system to converge towards the global minimum electronic configuration using such an approach: - change the smearing method (efmod in case.in2), i.e. use GAUSS for instance with large eval value at the beginning to 0.05 - reduce progressively eval But it should also be due to an incorrect model for the high pressure structure: - because you do not have enough or accurate experimental data - because the supercell you have generated exhibits an ordering which lead to the opening of a band gap. Regards Xavier kongshi a ?crit: Dear WIEN2k users: Recently I'm calculatingthe f-electron material under pressure with LDA+U.There are different results between with normal structure file and with supercell structure file. The result of normal structure file with symmetry under pressure is metal. But the supercell structure under pressure result is insulator.The result of spuercell structure file in atmospheric pressure is metal. In my opinion the pressure drive the material to the metal state. Can anybody tell me what the problem is? Thank you in advance. shi kong __ Information from ESET Smart Security, version of virus signature database 4821 (20100130) __ The message was checked by ESET Smart Security. http://www.eset.com ___ Wien mailing list Wien at zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien -- next part -- An HTML attachment was scrubbed... URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20100131/abc457e8/attachment.htm
[Wien] more than one slab calculation
Dear Xavier, Thank you very much for your suggestion. This will definitely help us to do the required calculations. 2010/1/31 Rocquefelte Xavier.Rocquefelte at cnrs-imn.fr shamik chakrabarti a ?crit : Dear Wien2k users, We can do surface calculation by creating one slab separated from the rest of the supercell. My question is can we create more than one slab in a single direction in Wien2k? YES We need slab calculation in which few slabs remain separated along say z direction. This is the definition of a supercell calculation for slabs. Lets consider a slab in the (a,b) plane. After creating this slab (slab width 4 angstrom) you simply need to change the c parameter (14 angstrom for instance) and recalculate the z-coordinates in order to include some vacuum (10 angstrom) between the slabs (given by the periodicity along c). Regards Xavier Thank you in advance... Shamik Chakrabarti Research Scholar IIT Kharagpur INDIA -- ___ Wien mailing listWien at zeus.theochem.tuwien.ac.athttp://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien ___ Wien mailing list Wien at zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien -- next part -- An HTML attachment was scrubbed... URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20100131/1ef8e02c/attachment.htm
[Wien] more than one slab calculation
Yes, I got a pdf file from Weishan, but I also need the original ppt file in order to make corrections. Cheers, Yia-Chung Chang Director Research Center for Applied Sciences Academia Sinica
