XC: Difference between revisions
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Description: {{TAG|XC}} specifies a combination of exchange-correlation functionals. | Description: {{TAG|XC}} specifies a combination of exchange-correlation functionals. | ||
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A combination of semilocal (LDA, GGA, and METAGGA) functionals can be set with the {{TAG|XC}} tag. The functionals that can be combined are the functionals implemented in VASP (listed at {{TAG|GGA}} and {{TAG|METAGGA}}) and the functionals implemented in Libxc{{cite|marques:cpc:2012}}{{cite|lehtola:sx:2018}}{{cite|libxc}} (listed on the Libxc website{{cite|libxc_list}}). The combination can consist of up to 100 components; for each, a multiplication factor can be set with the {{TAG|XC_C}} tag. Note that the {{TAG|XC}} tag is currently limited to the semilocal functionals, and can therefore not be used for other types of exchange-correlation approximations like Hartree-Fock ({{TAG|LHFCALC}}) or the van der Waals functionals ([[:Category:Van_der_Waals_functionals|Van_der_Waals_functionals]]). | A combination of semilocal (LDA, GGA, and METAGGA) functionals can be set with the {{TAG|XC}} tag, which provides much more flexibility in the choice of the functional compared to the {{TAG|GGA}} and {{TAG|METAGGA}} tags. The functionals that can be combined are the functionals implemented in VASP (listed at {{TAG|GGA}} and {{TAG|METAGGA}}) and the functionals implemented in Libxc{{cite|marques:cpc:2012}}{{cite|lehtola:sx:2018}}{{cite|libxc}} (listed on the Libxc website{{cite|libxc_list}}). The combination can consist of up to 100 components; for each, a multiplication factor can be set with the {{TAG|XC_C}} tag. Note that the {{TAG|XC}} tag is currently limited to the semilocal functionals, and can therefore not be used for other types of exchange-correlation approximations like Hartree-Fock ({{TAG|LHFCALC}}) or the van der Waals functionals ([[:Category:Van_der_Waals_functionals|Van_der_Waals_functionals]]). | ||
== Examples of {{FILE|INCAR}} == | == Examples of {{FILE|INCAR}} == | ||
Revision as of 10:03, 31 January 2024
XC = Combination of functionals
| Default: XC | = GGA | if the GGA tag is used |
| = METAGGA | if the METAGGA tag is used | |
| = The functional specified by LEXCH in the POTCAR file | if neither GGA nor METAGGA is used |
Description: XC specifies a combination of exchange-correlation functionals.
A combination of semilocal (LDA, GGA, and METAGGA) functionals can be set with the XC tag, which provides much more flexibility in the choice of the functional compared to the GGA and METAGGA tags. The functionals that can be combined are the functionals implemented in VASP (listed at GGA and METAGGA) and the functionals implemented in Libxc[1][2][3] (listed on the Libxc website[4]). The combination can consist of up to 100 components; for each, a multiplication factor can be set with the XC_C tag. Note that the XC tag is currently limited to the semilocal functionals, and can therefore not be used for other types of exchange-correlation approximations like Hartree-Fock (LHFCALC) or the van der Waals functionals (Van_der_Waals_functionals).
Examples of INCAR
XC = PE PS XC_C = 0.5 0.5
XC = SCAN_X PBE_C
- 70% of B88[7] (from Libxc) and 30% of PBE[5] (from VASP) for exchange and 100% of LYP for correlation[8] (from Libxc)
XC = GGA_X_B88 PBE_X GGA_C_LYP XC_C = 0.7 0.3 1.0
Related tags and articles
XC_C, GGA, METAGGA LIBXC1, LIBXC2, ALDAX, ALDAC, AGGAX, AGGAC, AMGGAX, AMGGAC
References
- ↑ M. A. L. Marques, M. J. T. Oliveira, and T. Burnus, Comput. Phys. Commun., 183, 2272 (2012).
- ↑ S. Lehtola, C. Steigemann, M. J. T. Oliveira, and M. A. L. Marques, SoftwareX, 7, 1 (2018).
- ↑ https://libxc.gitlab.io
- ↑ https://libxc.gitlab.io/functionals/
- ↑ a b c d J. P. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Lett., 77, 3865 (1996).
- ↑ J. P. Perdew, A. Ruzsinszky, G. I. Csonka, O. A. Vydrov, G. E. Scuseria, L. A. Constantin, X. Zhou, and K. Burke, Phys. Rev. Lett. 100, 136406 (2008).
- ↑ A. D. Becke, Density-functional exchange-energy approximation with correct asymptotic behavior, Phys. Rev. A 38, 3098 (1988).
- ↑ C. Lee, W. Yang, and R. G. Parr, Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density, Phys. Rev. B 37, 785 (1988).