Thank you very much for the detailed explanation again Professor Blaha. I will follow your suggestion and stop the current calculation, and starting from the simple cases with a lower RKmax.
PS: the cpu usage for the lapw1c is mostly at around 100% and the memory at around 77% in 'top' In the case.output1dn(up) I can see that the CUP time in interstitial (total) 15.44(15.29), and the cpu time in dstart: 104.55(103.89) - are we talking about the wall time is the dstart time? (I can not see anywhere says 'wall-time' in both files)- so this means my computer does not have enough memory (for this calculation)? Thank you very much for your time. kind regards, Qiwen ------Original Message------ From:"Peter Blaha"<pblaha at theochem.tuwien.ac.at> To:"A Mailing list for WIEN2k users"<wien at zeus.theochem.tuwien.ac.at> Cc: Subject:Re: [Wien] Would like to have some guidance from you Date:07/07/2011 09:02:27 AM(+0200) >As a beginner, you need to gain experience. > >So first start with pure A2BO4. Does it run properly, check timings,... >Then create first a smaller supercell, eg. a 2x2x1 cell. Does it run ? >timings (4 times as many atoms, --> without iterative diag. ~ 64 times >as long cpu-time in lapw1. However, in the supercell you can use 4 times >less k-points, s the total effort does NOT increase that much. > >For the large cell: use the top command to check the performance of >lapw1 or lapw2. In particular you should see of it uses the cpu by nearly >100 (or 200 when OMP_NUM_THREAD=2) %, or it does not becuase it does not >have enough memory and "pages". > >Also check the timings listed in case.output1up/dn. Is the cpu-time and >wall-time similar ? >If wall-time is much larger, your computer does not have enough memory. > >k-points: You heard at the workshop about k-points: metal-insulator or >small-large cells. >most likely I would not start out with so many k-points, but I don't know the >details >of your system. Of course 50-kpoints will run 4 times faster than 200 k. > >Another hint: For large cells you do not want to start out with RKMAX=7 (the >default). >Start the calculation with RKMax=6 or even 5.5. Run to scf, it should be MUCH >faster >(10-100 times !!!), but then don't stop, but increase RKMax and compare eg. >the forces >on all atoms, magnetic moments, DOS, (... what ever you are interested in) to >find a >reasonable RKMAX. > >And finally: For these large cells, iterative diagonalization should be used. > >I guess the most important message is: Start out with smaller problems. >Experiment >with parameters like k-points, RKmax, -it to get experience. > >Of course, a modern PC (or 4 of them for k-parallel runs) will help. But >checkout the >real bottleneck (memory ?) before. > >Am 07.07.2011 02:58, schrieb Dr Qi Wen YAO: >> Dear professor Blaha and Wien2k users, >> >> Thanks to the Wien2k Workshop, now that I can do some proper calculation but >> since i am new to Wien2k and I would like to have some guidance in my >> current calculation. >> >> I am doing a supercell (3x3x1) calculation (for publishing quality) to a >> layered structure perovskite A2BO4 compound. It is of K2NiF2 structure (SG >> I4/mmm), its resistivity is at around 0.001 Ohm-m at room temp so it is >> semi-conductive. >> >> Half of the "A" atoms (A atom is Sr in this case, and the B atom is Co) are >> replace by an Rare Earth atom so the whole supercell is of 90 atoms in size >> in my struct file. The original unit cell parameters were a=b=3.8 Amstrong >> and c=12.3 Amstrong. >> >> I am using a PC with 2 core Xeon 2.4GHz, 4G RAM running latest Susie, latest >> Wien2k and ifort11. >> >> The calculation is Spin Polarized (and not an anti-ferromagnetic as I know >> that this compound is ferromagnetic), I used 200 k-points for the current >> calculation. >> >> The initialization seems working fine (thanks to professor Blaha's guidance >> in the workshop). >> >> Now it seems that the calculation is a bit too much for this computer - it >> runs painfully slow and after two days, it only just displays to me two >> lines: "LAPW0 END" and "LAPW1 END". >> >> I am wondering: for this calculation, can I use less k-points say 50 (as it >> is a big cell) and the result would still be good enough for paper >> publishing? >> >> What kind of speed up do I expect if I am to use a 50 k-pints instead of 200 >> k-points? >> >> Would you think that a computer with i7 core and 16GB of RAM would be able >> to run this calculation without too much trouble (I am trying to convince my >> boss to purchase a new PC for me for WIEN2k)? >> >> Any comments/feedback would be greatly appreciated. >> >> Thank you for your time. >> >> kind regards, >> Qiwen >> >> ********************************************************** >> >> Dr QiWen YAO >> >> JSPS Fellow >> Multifunctional Materials Group >> Optical and Electronic Materials Unit >> Environment and Energy Materials Research Division >> >> National Institute for Materials Science >> >> 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan >> Phone: +81-29-851-3354, ext. no. 6482, Fax: +81-29-859-2501 >> >> ********************************************************** >> >> _______________________________________________ >> Wien mailing list >> Wien at zeus.theochem.tuwien.ac.at >> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > >-- > > P.Blaha >-------------------------------------------------------------------------- >Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna >Phone: +43-1-58801-15671 FAX: +43-1-58801-15698 >Email: blaha at theochem.tuwien.ac.at WWW: >http://info.tuwien.ac.at/theochem/ >-------------------------------------------------------------------------- >_______________________________________________ >Wien mailing list >Wien at zeus.theochem.tuwien.ac.at >http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien ********************************************************** Dr QiWen YAO JSPS Fellow Multifunctional Materials Group Optical and Electronic Materials Unit Environment and Energy Materials Research Division National Institute for Materials Science 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan Phone: +81-29-851-3354, ext. no. 6482, Fax: +81-29-859-2501 **********************************************************