volume optimization

Message

zsoltrak · #1 Post by **zsoltrak** » Tue Feb 26, 2013 7:57 pm

Hi all,

I am calculating the properties of several f-electron compounds. I would like to ask the users' opinion about the volume optimization in an f-electron system: which way is better, with LDA/GGA or with LDA+U/GGA+U?

thanks,
Zs

#2 Post by **admin** » Thu Feb 28, 2013 1:58 pm

The LDA/GGA+U techniques are developed to correct band energies of non-bonding electrons. This should not influence the cell volume.

zsoltrak · #3 Post by **zsoltrak** » Thu Feb 28, 2013 5:05 pm

Dear admin,

Thank you for the reply. I agree with your comment, that there is no fundamental physical reason to use LDA+U/GGA+U methods for volume optimization. However, we observe a change in the lattice parameters when we go from LDA/GGA to LDA+U/GGA+U. Also, from a brief search of the literature we found that, in many cases, people tune the Hubbard-U parameter to reproduce the experimental lattice constants.
I would appreciate further thoughts and insights into this issue ...

Thanks,
Zs.