<div>Hi Laurence, Pavel and all Wien users,</div> <div>Thanks for your suggestion. I have done ground state calculation of hematite as non-magnetic, spin-polarised and antiferromagnetic way.No scf convergence problem. The supercell contains 120 number of atoms.But on the basis of your suggestion, now I will treat the supercell in antiferromagnetic way becoz hematite is antiferromagnetic at 0K.</div> <div>Regards.</div> <div>Swati</div> <div><BR><B><I>Laurence Marks <L-marks@northwestern.edu></I></B> wrote:</div> <BLOCKQUOTE class=replbq style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">The answer to this is that you have to think about the physics of your<BR>problem, and setup a calculation which is representative of this. If<BR>you pose the physics very badly in general you will get nowhere; the<BR>iterations may not coverge, the forces will be inconsistent and the<BR>results rubbish. Key things:<BR>1) Read the UG carefully, as
well as the other notes on the web pages<BR>so you understand the underlying physics.<BR>2) Don't just use an RKMAX, think about the plane wave sampling<BR>(RKMAX/min(RMT)) as well. For instance, this should be at least 3.5<BR>for a "good" calculation.<BR>3) Think about what the k-point sampling means. 1 k-pt for a small<BR>supercell is not reasonable.<BR>4) Think about whether it is reasonable to run Fe2O3 without spin. Fe<BR>is magnetic, so you are trying to run a spin-polarized system without<BR>spin which is incorrect physics.<BR>5) Think about whether it is reasonable to run Fe2O3 using simple GGA,<BR>or if this will give incorrect physics.<BR><BR>On Mon, Jun 16, 2008 at 6:19 AM, swati chaudhury <SWATI@RCAIS.RES.IN>wrote:<BR>> Dear all Wien users,<BR>> I am having problems with convergence of supercell of<BR>> hematite (Fe2O3, non-magnetic).<BR>> I have tried by changing so many parameters like mixing factor<BR>> (PRATT/BROYD/MSEC with
0.05,0.01,0.10,0.40), global E-parameter (0.35,0.30),<BR>> K-points (1,8) etc. So I am now little bit confused that is there any other<BR>> parameters, which can help to convergence scf cycle.<BR>> Basic inputs:<BR>> Supercell : 2x2x1 with 10 bohr slab<BR>> Space group=147 (P –3)<BR>> 13 GGA, -9.0 cut-off value, Rkmax =5.40, Emin = -9.0, Emax = 2.50, 14 - Gmax<BR>> Please help.<BR>> Thanks in advance.<BR>> Regards.<BR>> Swati.<BR>> _______________________________________________<BR>> Wien mailing list<BR>> Wien@zeus.theochem.tuwien.ac.at<BR>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien<BR>><BR>><BR><BR><BR><BR>-- <BR>Laurence Marks<BR>Department of Materials Science and Engineering<BR>MSE Rm 2036 Cook Hall<BR>2220 N Campus Drive<BR>Northwestern University<BR>Evanston, IL 60208, USA<BR>Tel: (847) 491-3996 Fax: (847) 491-7820<BR>email: L-marks at northwestern dot edu<BR>Web:
www.numis.northwestern.edu<BR>Commission on Electron Diffraction of IUCR<BR>www.numis.northwestern.edu/IUCR_CED<BR>_______________________________________________<BR>Wien mailing list<BR>Wien@zeus.theochem.tuwien.ac.at<BR>http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien<BR></BLOCKQUOTE><BR>