Dear Marcos: I have confirmed with the developer of that part (Daniel Sanchez) and his answer is:
Yes, the same Ueff will give the same final results. The current implementation follows the work of Dudarev et. al. The plan is to change it for a more rigorous implementation in a future, though. Yours, -- Jose A. Torres, Ph.D. Manager of the SIESTA Software tel: +34 914973805 from Marcos Veríssimo Alves <[email protected]> reply-to [email protected] to [email protected] date Thu, Jan 7, 2010 at 4:21 PM subject [SIESTA-L] Doubt on LDA+U Hi all, I have a doubt on the LDA+U implementation in siesta, more specifically on the definition of U and J. The siesta LDA+U manual states that "although the input allows to define independent values of the U and J parameters for each atomic shell, in the actual calculation the two parameters are combined to produce an effective Coulomb repulsion U_{eff}=U-J. U_{eff} is the parameter actually used in the calculation for the time being.". Now, does that really mean what it seems to imply, namely that any combination of U and J that produces a given U_{eff} will give me the same final results? For example, if I want my U_{eff} to be 1.0 eV, then U=0.6, J=0.4 and U=1.4 and J=-0.4 will give me the same final results? Cheers, Marcos --
