Dear all,
During the PW-DFT calculations, how do you determine the occurrence of total energy convergence vs. energy cutoff for wavefunctions? I mean is that ok when the total energy difference is less than a certain value (e.g. 0.1 %) or when the total energy difference per atom is less than some values (e.g. 5 mRyd/atom)?
I'm using Quantum Espresso 6.1.
The very simple way is to just do the calculations with different cutoff values in a particular range and then try to check by plotting a graph a between Total energy and cut off values. Try to find the the value of cutoff after which you will get a line parallel to x-axis means after that there will be enrgy convergence and you can use that value for further calculations.
Check the graph attached below.
Dear Abhinav, I understand you but my question is that what is the convergence criteria? I need a value; it would be more scientific this way.
Hi Sayyed,
An acceptable error on energy differences is generally ~5 meV/atom !
Best,
Sanjiv
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