Unit of total force in QE

Posted In DFT (Quantum Espresso)
  • Hải Nguyễn Thanh 1 year ago

    Dear Materials Square users,


    I am using Quantum Espresso for DFT calculation. However, I am very confusing about forc_conv_thr parameter.

    I read a lot of papers, they only mentioned the max force in eV/Å. In Materials Square, the force threshold is defined as Ry/bohr. Is this correct that I have to convert the value from eV/Å to Ry/bohr.

    For instance, 0.05 eV/Å is equal to 0.0019 Ry/bohr. 0.05 eV/Å is equal to 0.00038 Ry/bohr.

    Am I correct? please correct me if I am missing something.

    Thank you very much for your time and consideration.




  • 2lihf4bm@gmail.com 1 year ago



    As you know, the 'eV/Å' is the majorly used unit. But QE uses 'Ry/Bohr' instead.


    So you should convert the unit to Ry/Bohr when setting the force threshold on QE.

    The 0.01 eV/Å is corresponded to around 0.00038 Ry/Bohr.

    This is why Materials Square uses the 'forc_conv_thr = 0.00038' as the default.


    Thank you.


  • Hải Nguyễn Thanh 1 year ago

    Thank you very much for kind comment.


    I am clear now. 

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