QuantumATK Forum
QuantumATK => General Questions and Answers => Topic started by: esp on October 1, 2012, 23:21
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how do I check the status of a calculation? I mean, if i am doing a transmission calculation, for example, what can I read from the output log to tell me how far along it is? i dont like waiting 12 hours and not knowing if it is 10% done, 50% done ... i just have no idea ... are there any markers in the output I can search for?
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It's tricky to predict when a calculation will converge, but obviously the dE and dH tell you how far from convergence you are. And if you are just waiting for the transmission spectrum (after it's converged), well, there is a progress bar...
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To my surprise, a trans calculation that was running for 17 hours, just for the density calculation, now takes like 2 hours to complete that portion .. my trick? all I did was increase the number of history steps to 40 .... maybe i will try 100 .. how can I estimate how much memory is needed for increasing this number?
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History steps is a double-edged sword - for some systems it helps to increase, for others to decrease. But if you do increase it costs in memory, and I doubt you will gain much beyond 40 steps. How many steps does it take anyway? More than 40?
We have a new script coming out with 12.8 that lets you check (roughly) the expected memory usage of a calculation (in serial). You can catch a glimpse of this at http://quantumwise.com/documents/tutorials/ATK-12.8/MemoryUsage (link may change later); to use it you need the 12.8.b1 version.
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If I simply count the steps as it is doing the iterations, then it looks like something between 30 and 40 ... i did not realize that iteration number is what the history steps were ... in any case 20 hours down to 2 is fine with me .. i understand though it is not always the case as much as I wish it were ...
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That also means if you find 40 history steps uses too much memory, you may be able to get the same number of iterations with 20 or 15 history steps.