|
|
| Line 13: |
Line 13: |
| {{NB|important|To get correct results with meta-GGA functionals (see discussion at {{TAG|LTBOUNDLIBXC}}), it is necessary to use Libxc from version 5.2.0 onwards (or the master version for the latest implemented functionals) and to [[Makefile.include#Libxc_.28optional.29|compile it with the option <code>--disable-fhc</code>]].}} | | {{NB|important|To get correct results with meta-GGA functionals (see discussion at {{TAG|LTBOUNDLIBXC}}), it is necessary to use Libxc from version 5.2.0 onwards (or the master version for the latest implemented functionals) and to [[Makefile.include#Libxc_.28optional.29|compile it with the option <code>--disable-fhc</code>]].}} |
|
| |
|
| == How to ==
| |
|
| |
|
| The allowed possibilities for {{TAG|LIBXC1}} and {{TAG|LIBXC2}} are the following:
| |
| *Both {{TAGDEF|LIBXC1}} and {{TAG|LIBXC2}} are specified and correspond to exchange and correlation functionals, respectively.
| |
| *Only {{TAGDEF|LIBXC1}} is specified and corresponds to an exchange or exchange-correlation functional. {{NB|warning|If {{TAGDEF|LIBXC1}} is an exchange-correlation functional, then {{TAGDEF|LIBXC2}} can not be used.|:}}
| |
| *{{TAGDEF|LIBXC1}} and {{TAG|LIBXC2}} can correspond to functionals of different families, e.g., a meta-GGA and a GGA, respectively.
| |
|
| |
|
| Regarding other tags in {{FILE|INCAR}} related to Libxc:
| | {{sc|LIBMBD_METHOD|Examples|Examples that use this tag}} |
| *One also has to specify {{TAG|GGA}} = LIBXC for LDA, GGA and GGA-based hybrid functionals or {{TAG|METAGGA}} = LIBXC for meta-GGA functionals and meta-GGA-based hybrid functionals. Note that if one of the tags ({{TAGDEF|LIBXC1}} or {{TAGDEF|LIBXC2}}) corresponds to a meta-GGA, while the other corresponds to a GGA or LDA, then {{TAG|METAGGA}} = LIBXC (and not {{TAG|GGA}} = LIBXC) has to be specified.
| |
| *Many of the functionals implemented in Libxc have parameters that can be modified. This can be done via the tags {{TAG|LIBXC1_Pn}} and {{TAG|LIBXC2_Pn}}, where <math>n=1, 2, \ldots</math>.
| |
| *The tag {{TAG|LTBOUNDLIBXC}}, which is .FALSE. by default, allows to enforce the lower bound on the kinetic-energy density (<math>\tau_{\sigma}^{\mathrm{W}}<\tau_{\sigma}</math>) with <math>\tau_{\sigma}=\max(\tau_{\sigma},\tau_{\sigma}^{\mathrm{W}})</math> before <math>\tau_{\sigma}</math> is used in a meta-GGA functional from Libxc.
| |
| | |
| For calculations with hybrid functionals ({{TAG|LHFCALC}}=True), the following provides some explanations:
| |
| *The Libxc functionals whose tag starts with HYB already include the mixing parameter. Therefore, for them, the {{TAG|ALDAX}}, {{TAG|ALDAC}}, {{TAG|AGGAX}}, {{TAG|AGGAC}}, {{TAG|AMGGAX}}, and {{TAG|AMGGAC}} tags can not be used (more information on how to modify the mixing and screening parameters can be found at {{TAG|LIBXC1_Pn}}).
| |
| *If the semilocal component of the hybrid functional is constructed using Libxc functionals that do not contain HYB in the tag, then {{TAG|ALDAX}}, {{TAG|AGGAX}}, {{TAG|ALDAC}}, and {{TAG|AGGAC}} will be used and multiply
| |
| :<math>E_{\mathrm{x}}^{\mathrm{LDA}}=\int\epsilon_{\mathrm{x}}^{\mathrm{LDA}}(n)d^{3}r</math>
| |
| :<math>\Delta E_{\mathrm{x}}^{\mathrm{GGA}}=\int\left(\epsilon_{\mathrm{x}}^{\mathrm{GGA}}(n,\nabla n) - \epsilon_{\mathrm{x}}^{\mathrm{LDA}}(n)\right)d^{3}r</math>
| |
| :<math>E_{\mathrm{c}}^{\mathrm{LDA}}=\int\epsilon_{\mathrm{c}}^{\mathrm{LDA}}(n)d^{3}r</math>
| |
| :<math>\Delta E_{\mathrm{c}}^{\mathrm{GGA}}=\int\left(\epsilon_{\mathrm{c}}^{\mathrm{GGA}}(n,\nabla n) - \epsilon_{\mathrm{c}}^{\mathrm{LDA}}(n)\right)d^{3}r</math>
| |
| :respectively, where <math>\epsilon_{\mathrm{x}}^{\mathrm{LDA}}(n)=-\left(3/4\right)\left(3/\pi\right)^{1/3}n^{4/3}</math> and <math>\epsilon_{\mathrm{c}}^{\mathrm{LDA}}(n)=\epsilon_{\mathrm{c}}^{\mathrm{GGA}}(n,\nabla n=0)</math>.
| |
| | |
| == Examples of {{FILE|INCAR}} ==
| |
| | |
| *PBE{{cite|perdew:prl:1996}}
| |
| {{TAG|GGA}} = LIBXC
| |
| {{TAG|LIBXC1}} = GGA_X_PBE # or 101
| |
| {{TAG|LIBXC2}} = GGA_C_PBE # or 130
| |
| | |
| *SCAN{{cite|sun:prl:15}}
| |
| {{TAG|METAGGA}} = LIBXC
| |
| {{TAG|LIBXC1}} = MGGA_X_SCAN # or 263
| |
| {{TAG|LIBXC2}} = MGGA_C_SCAN # or 267
| |
| | |
| *PBEh (PBE0){{cite|adamo:jcp:1999}}
| |
| {{TAG|LHFCALC}} = .TRUE.
| |
| {{TAG|AEXX}} = 0.25
| |
| {{TAG|GGA}} = LIBXC
| |
| {{TAG|LIBXC1}} = HYB_GGA_XC_PBEH # or 406
| |
| | |
| *SCAN0
| |
| {{TAG|LHFCALC}} = .TRUE.
| |
| {{TAG|AEXX}} = 0.25
| |
| {{TAG|METAGGA}} = LIBXC
| |
| {{TAG|LIBXC1}} = MGGA_X_SCAN # or 263
| |
| {{TAG|LIBXC1}} = MGGA_C_SCAN # or 267
| |
| | |
| == Related tags and articles ==
| |
| {{TAG|LIBXC2}},
| |
| {{TAG|LIBXC1_Pn}},
| |
| {{TAG|LIBXC2_Pn}},
| |
| {{TAG|LTBOUNDLIBXC}},
| |
| {{TAG|GGA}},
| |
| {{TAG|METAGGA}},
| |
| {{TAG|LHFCALC}},
| |
| {{TAG|AEXX}},
| |
| {{TAG|ALDAX}},
| |
| {{TAG|ALDAC}},
| |
| {{TAG|AGGAX}},
| |
| {{TAG|AGGAC}},
| |
| {{TAG|AMGGAX}},
| |
| {{TAG|AMGGAC}},
| |
| [[list_of_hybrid_functionals|List of hybrid functionals]]
| |
| | |
| {{sc|LIBXC1|Examples|Examples that use this tag}} | |
|
| |
|
| == References == | | == References == |
| Line 82: |
Line 21: |
|
| |
|
| ---- | | ---- |
| [[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:GGA]][[Category:meta-GGA]][[Category:Hybrid_functionals]] | | <!--[[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:GGA]][[Category:meta-GGA]][[Category:Hybrid_functionals]]--> |
LIBMBD_METHOD = [string]
Description: LIBMBD_METHOD selects one of the van der Waals methods available in the library libMBD of many-body dispersion methods[1][2][3].
| Important: This feature is available from VASP.6.3.0 onwards that needs to be compiled with -DUSELIBXC.
|
LIBXC1 and LIBXC2 can be set to a label (string) or number (integer) associated with a functional listed on the Libxc website[4], e.g., GGA_X_PBE and 101 for PBE exchange. The label indicates if this is an exchange (X), correlation (C), or exchange-correlation (XC) functional, and which family it belongs to, namely LDA (LDA or HYB_LDA), GGA (GGA or HYB_GGA) or meta-GGA (MGGA or HYB_MGGA). If LIBXC1 corresponds to an exchange functional, then it can be used in combination with LIBXC2 for the correlation functional.
Libxc is a separate library package that has to be downloaded[5] and compiled before VASP is compiled with the corresponding precompiler options and links to the libraries.
Calculations with Laplacian-dependent meta-GGA functionals and meta-GGA-based hybrid functionals are possible since VASP.6.4.0.
| Warning: Do not use the Libxc functionals that are hybrid-MGGA-exchange-only, i.e., those whose label starts with HYB_MGGA_X, since the results will be wrong.
|
Important: To get correct results with meta-GGA functionals (see discussion at LTBOUNDLIBXC), it is necessary to use Libxc from version 5.2.0 onwards (or the master version for the latest implemented functionals) and to compile it with the option --disable-fhc.
|
Examples that use this tag
References
