[Pw_forum] On line DFT calculations

[Lorenzo Paulatto]

Replying to message "[Pw_forum] On line DFT calculations" from nand  
(11/06/10):
> I am trying to do some supercell calculations for Mn Doped GaAs. How  
> ever my RAM is not sufficient and the time taken by these calculations  
> too long for my PC. I would like to know if there is any online facility  
> where i can do these large supercell calculations.

None that I know: disk space is cheap, but computational time is  
expensive. However, your university or institution may provide some  
computing facility. You can also apply for interantional grants of  
computing time, of course the scale of times in this case is long.

> Also can any one tell how much RAM is required for a 64 atom supercell  
> calculations. Any other suugestion that can help.

It is written during the run, e.g.
per-process dynamical memory:    52.3 Mb

if you have it for a smaller supercell you can consider that it scales  
more or less with the cube of the unit cell  
<http://www.quantum-espresso.org/user_guide/node46.html>


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Lorenzo Paulatto
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