Hi LDM The unit cell of Nd is hexagonal, space group *P63/mmc* (#194), Pearson Symbol: hP4 with lattice parameters: a= 3.659(3), c= 3.659(3) according to B.J.Beaudry, P.E. Palmer, "The Lattice parameters of La, Ce, Pr, Nd, Sm, Eu AND Yb", J. Less-Common Metals, 34 (1974) 225 - 231.
The interatomic distances are 3.628A to 3.659A. So yes, these are large distances. I can use smaller RMT for Nd and/or HDLOs. Why do I need the same RMT of element when comparing different phases with that element? Victor בתאריך יום ה׳, 17 בינו׳ 2019 ב-23:58 מאת Laurence Marks < l-ma...@northwestern.edu>: > Dear Viktor, > > Let me add something about large RMTs. I have noticed in the past that, in > general, the gradient at the RMT calculated from both sides (x RMTCheck) > is very similar, e.g. > > Atom 1 O | RMT Charge 0.489 Grad 0.690 | Step Charge 0.00136, > 0.00000 Gradient 0.2655, -0.2655 O > > The last two numbers should sum to almost zero. However, with very large > RMTs they can deviate from this, particularly when the gradient is small. I > think this leads to anomalies at the RMT. (Peter would say that the > linearization is breaking down with an inadequate basis set, or something > similar.) Reducing the RMTs generally avoids this. > > While it is true that larger RMTs are "better" in terms of speed for a > single iteration, slightly smaller RMTs which may take longer for a single > iteration but are more stable so require fewer iterations can be nett > faster. Speed is not the same as stability and convergence, and often they > oppose each other. (Think about the tradeoff with condenser aperture size: > smaller is more coherent but more drift...) > > N.B., are you really sure that the Nd distances are that large? > > On Thu, Jan 17, 2019 at 3:31 PM Peter Blaha <pbl...@theochem.tuwien.ac.at> > wrote: > >> RMTs: Make sure that you choose RMTs, which can be used in all >> elemental solids, but the same should also be used in your compound. >> >> Yes, you can use very large RMTs if you follow the recommendations >> during init_lapw: >> Use HDLOs for f and (as L.Marks mentioned) probably d. >> Use lvns=6 (or 8) in case.in1 >> >> For a difficult system (and Nd with partially occupied 5f electrons is >> definitely a difficult systems), scf convergence can be more difficult. >> Thus, as mentioned before, use both -ec and -cc (at least 0.001; >> eventually a better cc is difficult to reach. Often you may need MORE >> than the default max of 40 scf cycles. So when runsp_lapw stops, make >> sure it does not stop beucause of the 40 it limits. >> Clearly, your energies with :dis=0.2 are wrong. >> >> For the compound but also the elements, make sure to use "consistent >> RKMAX" values. >> If you use: Al Ti Nd (2.3,2.5,2.7) and for your compound you use >> RKMAX=8, than Al should be done with RKMAX=8, Ti with RKmax=8*2.5/2.3, >> Nd with 8*2.7/2.3 >> >> Am 17.01.2019 um 21:19 schrieb Victor Zenou: >> > Dear Lauri >> > Thanks for your answer >> > I used only energy convergence criteria (10^-4). Still the charge >> > convergence was between 0.006 and 0.2 e. >> > The nearest neighbor distance is 6.856 a.u, I used RMT=2.7 a.u., summed >> > to 5.4 which is much lower than 6.856. Usually large RMT is preferred >> > to make the calculations as fast as possible. I plan to check a phases >> > in Al-Ti-Nd and I chose RMT equal to 2.3, 2.5 and 2.7 respectively. >> > Victor >> > >> > >> > >> > בתאריך יום ה׳, 17 בינו׳ 2019 ב-11:16 מאת Laurence Marks >> > <l-ma...@northwestern.edu <mailto:l-ma...@northwestern.edu>>: >> > >> > With such large RMT you certainly need HDLO for Nd, perhaps both d & >> > f. I would not want to use such large RMTs. >> > >> > Have you checked that the charge convergence is good? >> > >> > _____ >> > Professor Laurence Marks >> > "Research is to see what everybody else has seen, and to think what >> > nobody else has thought", Albert Szent-Gyorgi >> > http://www.numis.northwestern.edu < >> http://www.numis.northwestern.edu> >> > >> > On Thu, Jan 17, 2019, 03:04 Victor Zenou <za...@post.bgu.ac.il >> > <mailto:za...@post.bgu.ac.il> wrote: >> > >> > Hi >> > Here is updated question: >> > >> > Dear Wien2k users >> > >> > I'm using wien2k version 17.1 installed on Ubunto 18.04. >> > >> > I need to calculate the enthalpy of formation of few >> > intermetallic phases that include Nd. For that element I used >> > RMT=2.7 a.u. and RMT*Kmax=8.5 for spin-polarization calculations >> > via GGA-PBE. I didn't try spin-orbit coupling. Yet. >> > >> > The first stage is to choose proper k-points, which will give >> > accurate results (I used 1x10^-4 Ryd for energy convergence) on >> > one hand, but on the other hand won't be expensive in terms of >> > computing time. >> > >> > I noticed that there are large energy fluctuations (1x10^-2 Ryd; >> > which are 2 order of magnitude higher than the energy accuracy >> > (defined by convergence criterion), even when I went to 15,000 >> > k-points. Here is a list of energy as function of k-points: >> > >> > K-points IBZ E [Ryd] >> > >> > 100 8 -77040.4692 >> > >> > 500 38 -77040.4780 >> > >> > 1000 81 -77040.5062 >> > >> > 2000 120 -77040.5061 >> > >> > 3000 208 -77040.4391 >> > >> > 4000 244 -77040.4699 >> > >> > 5000 280 -77040.4878 >> > >> > 7500 455 -77040.4707 >> > >> > 10000 540 -77040.4881 >> > >> > 15000 840 -77040.4694 >> > >> > I would be happy to get an idea what could have gone wrong. >> > >> > Best regards, Victor >> > >> > >> > >> > בתאריך יום ד׳, 16 בינו׳ 2019 ב-13:59 מאת Victor Zenou >> > <za...@post.bgu.ac.il <mailto:za...@post.bgu.ac.il>>: >> > >> > Dear Wien2k users >> > >> > I'm using wien2k version 17.1 installed on Ubunto 18.04. >> > >> > As a part of investigation of intermetallic phases in >> > Al-Ti-Nd system, I need to calculate the enthalpy of >> > formation of few phases in that system. For that purpose, I >> > start calculating enthalpy (equal to energy at 0K) for each >> > element and phase at their optimal relaxed state. I used >> > spin-polarization calculations. (GGA-PBE) As advised in >> > Wien2k website I used the same RMT for each elements: 2.3, >> > 2.5 and 2.7 a.u. for Al, Ti and Nd, respectively. Also >> > proper RMT*Kmax (7.5 to Ti, 8.5 to Nd and 7.0 for the rest). >> > >> > The first stage is to choose proper k-points, which give you >> > accurate results (I used 1x10^-4 Ryd for energy convergence) >> > on one hand, but also some save computing time. >> > >> > The calculation for all elements and phases went OK, but Nd. >> > From certain k-points the energy fluctuated between 2 values >> > (differed by 1x10^-2). Attach a list of energy as function >> > of k-points: >> > >> > K-pointsIBZ E [Ryd] >> > >> > 1008-77040.4692 >> > >> > 50038-77040.4780 >> > >> > 100081-77040.5062 >> > >> > 2000120-77040.5061 >> > >> > 3000208-77040.4391 >> > >> > 4000244-77040.4699 >> > >> > 5000280-77040.4878 >> > >> > 7500455-77040.4707 >> > >> > 10000540-77040.4881 >> > >> > 15000840-77040.4694 >> > >> > I tried to get smart and did volume optimization using 4000 >> > k-points, later 5000 k-points. I got strange results. >> > >> > I would be happy to get an idea what could have gone wrong. >> > >> > I didn't try spin-orbit coupling >> > >> > Best regards, Victor >> > >> > _______________________________________________ >> > Wien mailing list >> > Wien@zeus.theochem.tuwien.ac.at <mailto: >> Wien@zeus.theochem.tuwien.ac.at> >> > >> https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=eK9aqsUgRkfDy2bZdzRW1MQXAt1xlSX8wLRVAOOVSLk&s=-x4eR4rPflykk4gZARg89aJRk1lrjzh4KhQaak_JByQ&e= >> > SEARCH the MAILING-LIST at: >> > >> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_index.html&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=eK9aqsUgRkfDy2bZdzRW1MQXAt1xlSX8wLRVAOOVSLk&s=aP3iF7UUFlgDwQ3l1Ge7GzYpkF2bqtTRb4xZCL-kRhM&e= >> > >> > >> > _______________________________________________ >> > Wien mailing list >> > Wien@zeus.theochem.tuwien.ac.at >> > >> https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=eK9aqsUgRkfDy2bZdzRW1MQXAt1xlSX8wLRVAOOVSLk&s=-x4eR4rPflykk4gZARg89aJRk1lrjzh4KhQaak_JByQ&e= >> > SEARCH the MAILING-LIST at: >> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_index.html&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=eK9aqsUgRkfDy2bZdzRW1MQXAt1xlSX8wLRVAOOVSLk&s=aP3iF7UUFlgDwQ3l1Ge7GzYpkF2bqtTRb4xZCL-kRhM&e= >> > >> >> -- >> -------------------------------------------------------------------------- >> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna >> Phone: +43-1-58801-165300 FAX: +43-1-58801-165982 >> Email: bl...@theochem.tuwien.ac.at WIEN2k: >> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.wien2k.at&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=eK9aqsUgRkfDy2bZdzRW1MQXAt1xlSX8wLRVAOOVSLk&s=yscbD2URDxKhBSNrsUvCXygszqazvEKzTMM4mptFXqY&e= >> WWW: >> >> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.imc.tuwien.ac.at_tc-5Fblaha-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D-2D&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=eK9aqsUgRkfDy2bZdzRW1MQXAt1xlSX8wLRVAOOVSLk&s=fi0SsUcgDnugWH41GhhT5XyalNBmpXl8Mik8Y2ueAkI&e= >> >> _______________________________________________ >> Wien mailing list >> Wien@zeus.theochem.tuwien.ac.at >> >> https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=eK9aqsUgRkfDy2bZdzRW1MQXAt1xlSX8wLRVAOOVSLk&s=-x4eR4rPflykk4gZARg89aJRk1lrjzh4KhQaak_JByQ&e= >> SEARCH the MAILING-LIST at: >> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_index.html&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=eK9aqsUgRkfDy2bZdzRW1MQXAt1xlSX8wLRVAOOVSLk&s=aP3iF7UUFlgDwQ3l1Ge7GzYpkF2bqtTRb4xZCL-kRhM&e= >> > > > -- > Professor Laurence Marks > "Research is to see what everybody else has seen, and to think what nobody > else has thought", Albert Szent-Gyorgi > www.numis.northwestern.edu ; Corrosion in 4D: > MURI4D.numis.northwestern.edu > Partner of the CFW 100% program for gender equity, www.cfw.org/100-percent > Co-Editor, Acta Cryst A > _______________________________________________ > 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
