[Pw_forum] convergence test for chromium

[Lorenzo Paulatto]

In data 30 settembre 2009 alle ore 17:48:41, udayagiri sai babu  
<udayagiri3 at gmail.com> ha scritto:

> Dear all
> I did convergence tests for chromium. The ecut value i obtained for  
> energy converged to 1mRyd is 60Ryd! which i believe is very high for an  
> Ultra Soft PP can somebody tell me if i am doing something wrong. Given  
> below are my
> sample input file and ecut vs total energy.

Dear Udayagiri,
what about the cutoff for charge density?
One good procedure to find a nicely converged cutoff is to increase  
ecutwfc until it converges than set ecutrho to 4*ecutwfc and reduce  
ecutwfc keeping ecutrho fixed.

Maybe you can fix ecutrho to 240 and see how low you can go with ecutwfc

best regards


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Lorenzo Paulatto
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