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large systems Date: 2006/11/09 08:13 Name: JessK Hello, I tried to perform relaxation of large bulk, cell is 8x8x32 Angstrom, 160 atoms, cutoff 250 Ry. I tried different O(N) methods, but all of them crashed before first MD step with nontrivial reason like 'segmentation fault'. I tried to use different machines (intel em64t, cray xt3), but no luck. I think I have enough memory for this job. Any ideas? thanks, JK

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Re: large systems ( No.1 ) Date: 2006/11/09 11:04 Name: T.Ozaki Hi, Maybe yours is a memory problem. For the system consisting of 160 atoms, the conventional scheme is still faster than the O(N) method. Regards, TO Re: large systems ( No.2 ) Date: 2006/11/10 07:20 Name: JessK Hi, Indeed I tried to use 'band' scheme first, and the code used all my memory. So, i thought O(N) could help. thanks, JK Re: large systems ( No.3 ) Date: 2007/01/13 01:27 Name: jessK Dr. Ozaki, Yes, I realized that it is a memory issue. Using the cluster with 8Gb on each node I was able to run it (slow, but works). But on usual PC cluster with medium amount of memory (~4Gb) it is a big challenge, because the memory is not distributed over the nodes (so, increasing numbero of CPUs doesn't help). In fact, calculations of the same system with usual plane-wave code require much smaller amount of memory (~2Gb on node). This situation kills my attempts to apply OpenMX for the research. Is it possible to trace, why the code needs such huge amount of memory? thanks, JK

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