DFT+U: Difference between revisions
No edit summary |
No edit summary |
||
| Line 5: | Line 5: | ||
To perform a ''DFT + U'' calculation using ''VASP'' you just have to add the following flags to your ''INCAR'' file: | To perform a ''DFT + U'' calculation using ''VASP'' you just have to add the following flags to your ''INCAR'' file: | ||
---- | |||
GGA = PW | PB | LM | 91 | PE | RP | PS | AM → The value of this flag depens on the ''DFT'' functional you want to use)[http://cms.mpi.univie.ac.at/vasp/vasp/GGA_tag.html] | GGA = PW | PB | LM | 91 | PE | RP | PS | AM → The value of this flag depens on the ''DFT'' functional you want to use)[http://cms.mpi.univie.ac.at/vasp/vasp/GGA_tag.html] | ||
| Line 17: | Line 19: | ||
LASPH = .TRUE. → ''VASP'' recommends to add this flag to the ''INCAR'' file when using gradient corrected functionals. | LASPH = .TRUE. → ''VASP'' recommends to add this flag to the ''INCAR'' file when using gradient corrected functionals. | ||
---- | |||
Revision as of 14:03, 25 October 2012
go back to Main Page, Núria López and Group, Computational Resources, Chemistry & More, Group Pages
To perform a DFT + U calculation using VASP you just have to add the following flags to your INCAR file:
GGA = PW | PB | LM | 91 | PE | RP | PS | AM → The value of this flag depens on the DFT functional you want to use)[1]
LDAU = .TRUE.
LDAUL = "value" → It specifies the l-quantum number for which the on-site interaction is added (1 = p ; 2 = d ; 3 = f).
LDAUU = "value" → It specifies the effective on-site Coulomb interaction parameters (U).
LDAUJ = "value" → It specifies the effective on-site Exchange interaction parameters (J).
LASPH = .TRUE. → VASP recommends to add this flag to the INCAR file when using gradient corrected functionals.
IMPORTANT NOTES:
- In VASP there are several DFT + U approaches that can be used. You can specify the one you want by setting the corresponding value in the flag LDAUTYPE = "value". The default approach in VASP is the one introduced by Dudarev et al. (LDAUTYPE = 2).[2] For further details on this flag, see the online VASP manual.[3]
- The values in LDAUL, LDAUU and LDAUJ must be specified for all atomic species!
- The default value in VASP for LDAUL is 2, so do not forget to specify your correct values for this flag in your INCAR file!
- It is not meaningful to compare the total energies resulting from calculations with different U and/or J (c.q. U - J in case of Dudarev's approach).