[Pw_forum] questions about the calculation time

[Paolo Giannozzi]

On Nov 19, 2007, at 14:51 , Xinxin Yao wrote:

> The diagonalization process takes a few time about 5 minutes,
> but after the line "ethr =" appeares, until the next display of output
> file, it takes much long time than the former diagonalization process,
> larger than 10 minutes. What cost so much time in this process?

look at the time report, printed at the end of the calculation.
You can perform just one scf step if you do not want to wait
too much.

> And the cpu time is less than the real time.

I would be very surprised of the opposite. How much less?

> How could I improve the cpu efficiency?

you didn't specify the most basic pieces of information, i.e.
what the time reports says, whether you are running serially
or in parallel on how many processors on which communication
hardware. How can anybody answer?

Paolo
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Paolo Giannozzi, Dept of Physics, University of Udine
via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222