Self-consistent U determination

Determining the U parameter by a linear response approach

The Hubbard U parameter can be determined self-consistently by applying first order density functional perturbation theory (i.e. linear response theory), following the approach of Coccoccioni and de Gironcoli (here add reference)

  LDAU     = T               # Switch on LDA+U
  LDAUTYPE = 2               # LSDA + U Dudarev's approach = type 2 in .vasp

You will need to add the U and J term for each atom type. For example to put an effective U=1 for the second type of atom, you will put LDAUU=2 and LDAUJ=1 as follow:

  # Add on-site interaction for the respective atoms (same order as in POSCAR) 
  LDAUL =  -1   2    -1      # 2 for d-orbital interactions, -1 no on-site interaction
  LDAUU =  0.0  2.0   0      # Define U-parameters for on-site Coulomb interaction
  LDAUJ =  0.0  1.0   0      # Define J-parameters for on-site Exchange interaction
  LDAUPRINT = 0              # 0 to ignore, 1 to print occupation matrix in OUTC

Finally, this flag is used to speed up DFT+U calculation:

  LMAXMIX = 4  #DFT+U calculations may require LMAXMIX to 4 for d-electrons (or 6 for f-elements) for faster convergence to the groundstate

Back to Núria López and Group / Scripts_for_VASP.