Yes, XAS calculations for 100 atoms/cell should be possible on your computer. But note, the required resources may vary a lot with the specific system (atoms, nearest neighbor distances, structure (inversion symmetry).
With just 2 nodes and 4 cores in total, mpi-parallelization is most-likely not the way to go (except you need it because of memory limitations). For XAS you need a good DOS at the end, so you will need finally some k-points, thus k-parallelization should be fine, for a large system probably only 1 job per node (but with OMP_NUM_PTHREAD = 2). No, you don't need an explicit master node, except for NFS, i.e. your data should be on one node, but via NFS also available on the other one. Tomohiko Tasaka schrieb: > Hello, > > Thanks for your kind reply. if possible, could you advise me of the minimum > system to analyze core-orbital spectroscopy (e.g. x-ray absorption spectrum) > for a case with 100 atoms/cell? > for example, how about 2 machines which has dual cores with 4 GB RAM (total > 4 cores, 8 GB RAM)? is it sufficient on condition of mix parallelization? > > Further, I'd like to confirm whether these parallel jobs require a single > master (control) node to install much more requirement resources(e.g. RAM > or any I/O bandwidth) than client nodes. > > > Sorry, vague question. > Tomo > > -----Original Message----- > From: wien-bounces at zeus.theochem.tuwien.ac.at > [mailto:wien-bounces at zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha > Sent: Monday, September 01, 2008 10:24 PM > To: A Mailing list for WIEN2k users > Subject: Re: [Wien] memory configuration for k-point parallelization > > For a case with 100 atoms/cell most likely you will have only 1 k-point, > thus k-point parallel is not possible, only mpi-parallel. > > In case you have a metallic (magnetic) case, you may still have a few > k-points and than k-parallel is still most efficient, provided the > memory (RAM) is large enough ON EACH NODE (has nothing to do with the > master node). > > If you have enough nodes available, one can also mix k-point and > mpi-parallel > mode, eg. when you have 4-kpoints, but you have 16 nodes, run 4-mpi-jobs > per k-point. > > mpi-version only with the most recent versions. > > Tomohiko Tasaka schrieb: >> Dear wien2k users, >> >> >> >> I heard that the k-point parallel calculation with wien2k old version >> >> needs huge physical memory for a master node. The reason is that >> >> the master node (job submitting node) collects many distributed results >> >> which are calculated by each calculation node, at the same time. >> >> Therefore, there is difficulty in executing k-point parallel calculation >> >> for the large system (e.g. 100 atoms per unit cell). >> >> >> >> is this correct regardless of the version? please advise. >> >> >> >> Any information would be appreciated. >> >> >> >> With best regards, >> >> Tomo >> >> >> >> >> ------------------------------------------------------------------------ >> >> _______________________________________________ >> 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/ --------------------------------------------------------------------------