LDAUTYPE

LDAUTYPE = 1 | 2 | 4
Default: LDAUTYPE = 2 

Description: LDAUTYPE specifies the DFT+U variant that will be used.

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The following variants of the DFT+U approach are available:

• LDAUTYPE=1: The rotationally invariant DFT+U introduced by Liechtenstein et al.

• LDAUTYPE=2: The simplified (rotationally invariant) approach to DFT+U, introduced by Dudarev et al.

• LDAUTYPE=3: Linear response ansatz of Cococcioni et al. to compute U. See how to calculate U.

Mind: For LDAUTYPE=3, the LDAUU and LDAUJ tags specify the strength of the spherical potential acting on the spin-up and spin-down manifolds, respectively.

• LDAUTYPE=4: Same as LDAUTYPE=1, but without exchange splitting.

A method to estimate the parameters for DFT+U is the constrained-random-phase approximation. Another method is the linear response ansatz with LDAUTYPE=3, mentioned above. On the other hand, in many applications, the DFT+U parameters are used as tuning parameters to fit experimental data.

Tip: For band-structure calculations, increase LMAXMIX to 4 ($d$ elements) or 6 ($f$ elements).

This is because the CHGCAR file contains only information up to angular momentum quantum number set by LMAXMIX for the on-site PAW occupancy matrices. When the CHGCAR file is read and kept fixed in the course of the calculations (ICHARG=11), the results will necessarily not be identical to a self-consistent run. The deviations are often large for DFT+U calculations.

Warning: The total energy will depend on the parameters $U$ (LDAUU) and $J$ (LDAUJ). It is, therefore, not meaningful to compare the total energies resulting from calculations with different $U$ and/or $J$; or $U-J$ in the case of Dudarev's approach (LDAUTYPE=2).

It is possible to use LDAUTYPE=1, 2, and 3 for a non–spin-polarized calculation with ISPIN=1.

Related tags and articles

LDAU, LDAUL, LDAUU, LDAUJ, LDAUPRINT, LMAXMIX, DFT+U: formalism

Examples that use this tag

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